INTERNET-DRAFT
                                                                       R. deBry
                                                                IBM Corporation
                                                                    T. Hastings
                                                              Xerox Corporation
                                                                     R. Herriot
                                                               Sun Microsystems
                                                                    S. Isaacson
                                                                   Novell, Inc.
                                                                      P. Powell
                                                     San Diego State University
                                                                  July 14, 1997
         
                  Internet Printing Protocol/1.0: Model and Semantics
                              draft-ietf-ipp-model-03.txt
         
         Status of this Memo
         
         This document is an Internet-Draft.  Internet-Drafts are working
         documents of the Internet Engineering Task Force (IETF), its areas,
         and its working groups.  Note that other groups may also distribute
         working documents as Internet-Drafts.
         
         Internet-Drafts are draft documents valid for a maximum of six months
         and may be updated, replaced, or obsoleted by other documents at any
         time.  It is inappropriate to use Internet-Drafts as reference
         material or to cite them other than as "work in progress".
         
         To learn the current status of any Internet-Draft, please check the
         "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
         Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
         munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
         ftp.isi.edu (US West Coast).
         
         Abstract
         
         This document is one of a set of documents, which together describe
         all aspects of a new Internet Printing Protocol (IPP).  IPP is an
         application level protocol that can be used for distributed printing
         using Internet tools and technology.  The protocol is heavily
         influenced by the printing model introduced in the Document Printing
         Application (ISO/IEC 10175 DPA) standard.  Although DPA specifies both
         end user and administrative features, IPP version 1.0 is focused only
         on end user functionality.
         
         The full set of IPP documents includes:
         
         
         
         
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           Internet Printing Protocol: Requirements
           Internet Printing Protocol/1.0: Model and Semantics
           Internet Printing Protocol/1.0: Security
           Internet Printing Protocol/1.0: Protocol Specification
           Internet Printing Protocol/1.0: Directory Schema
         
         The requirements document takes a broad look at distributed printing
         functionality, and it enumerates real-life scenarios that help to
         clarify the features that need to be included in a printing protocol
         for the Internet.  It identifies requirements for three types of
         users: end users, operators, and administrators.  The requirements
         document calls out a subset of end user requirements that MUST be
         satisfied in the first version of IPP.  Operator and administrator
         requirements are out of scope for v1.0. The model and semantics
         document describes a simplified model with abstract objects, their
         attributes, and their operations. The model introduces a Printer
         object and a Job object.  The Job object supports multiple documents
         per job.  The security document covers potential threats and proposed
         counters to those threats.  The protocol specification is formal
         document which incorporates the ideas in all the other documents into
         a concrete mapping using clearly defined data representations and
         transport protocol mappings that real implementers can use to develop
         interoperable client and server side components. Finally, the
         directory schema document shows a generic schema for directory service
         entries that represent instances of IPP Printers.
         
         This document is the "Internet Printing Protocol/1.0: Model and
         Semantics" document.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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                                   Table of Contents
         
         1.   Simplified Printing Model......................................7
         2.   IPP Objects....................................................9
         2.1  Printer Object................................................10
         2.2  Job Object....................................................12
         2.3  Document Object...............................................13
         2.4  Object Relationships..........................................14
         2.5  Object Identity...............................................14
         3.   IPP Operations................................................15
         3.1  Operation Semantics...........................................16
         3.1.1     Get-Operations Operation.................................17
         3.1.1.1        Get-Operations Request..............................17
         3.1.1.2        Get-Operations Response.............................17
         3.1.2     Print-Job Operation......................................17
         3.1.2.1        Print-Job Request...................................18
         3.1.2.2        Print-Job Response..................................20
         3.1.3     Print-URI Operation......................................20
         3.1.3.1        Print-URI Request...................................20
         3.1.3.2        Print-URI Response..................................21
         3.1.4     Validate-Job Operation...................................21
         3.1.4.1        Validate-Job Request................................21
         3.1.4.2        Validate-Job Response...............................21
         3.1.5     Create-Job Operation.....................................22
         3.1.5.1        Create-Job Request..................................22
         3.1.5.2        Create Job Response.................................22
         3.1.6     Send-Document Operation..................................23
         3.1.6.1        Send-Document Request...............................23
         3.1.6.2        Send-Document Response..............................23
         3.1.7     Send-URI Operation.......................................23
         3.1.7.1        Send-URI Request....................................24
         3.1.7.2        Send-URI Response...................................24
         3.1.8     Cancel Job Operation.....................................24
         3.1.8.1        Cancel-Job Request..................................24
         3.1.8.2        Cancel-Job Response.................................25
         3.1.9     Get-Attributes Operation.................................25
         3.1.9.1        Get-Attributes Request..............................25
         3.1.9.2        Get-Attributes Response.............................27
         3.1.10    Get-Jobs Operation.......................................27
         3.1.10.1       Get-Jobs Request....................................27
         3.1.10.2       Get-Jobs Response...................................28
         3.2  Operation Status Codes and Messages...........................28
         4.   Object Attributes.............................................29
         4.1  Attribute Syntaxes............................................29
         4.1.1     Attribute Extensibility..................................31
         4.2  Job Template Attributes.......................................33
         4.2.1     job-name (name)..........................................37
         4.2.2     job-sheets (type4 keyword)...............................38
         
         
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         4.2.3     notify-events (1setOf type2 keyword).....................38
         4.2.4     notify-addresses (1setOf uri)............................38
         4.2.5     job-priority (integer(1:100))............................39
         4.2.6     job-hold-until (type4 keyword)...........................39
         4.2.7     multiple-documenthandling (type2 keyword)................40
         4.2.8     best-effort (boolean)....................................40
         4.2.9     media (type4 keyword)....................................42
         4.2.10    number-up (type3 keyword)................................42
         4.2.11    sides (type2 keyword)....................................43
         4.2.12    printer-resolution (type2 enum)..........................43
         4.2.13    print-quality (type2 enum)...............................44
         4.2.14    copies (integer(1:2**31 - 1))............................45
         4.2.15    finishing (1setOf type2 enum)............................45
         4.2.16    document-format (type2 keyword)..........................46
         4.2.17    compression (type3 keyword)..............................46
         4.2.18    job-k-octets (integer(0:2**31 - 1))......................46
         4.2.19    job-impressions (integer(0:2**31 - 1))...................46
         4.2.20    job-media-sheets (integer(0:2**31 - 1))..................47
         4.3  Job Description Attributes....................................47
         4.3.1     job-uri (uri)............................................48
         4.3.2     job-uri-user (uri).......................................49
         4.3.3     job-originating-user (name)..............................49
         4.3.4     job-originating-host (name)..............................49
         4.3.5     user-locale (locale).....................................49
         4.3.6     job-state (type1 enum)...................................49
         4.3.7     job-state-reasons (1setOf  type2 keyword)................51
         4.3.8     job-state-message (text).................................53
         4.3.9     output-device-assigned (name)............................53
         4.3.10    time-since-pending (milliseconds)........................53
         4.3.11    time-since-processing (milliseconds).....................53
         4.3.12    time-since-completed (milliseconds)......................53
         4.3.13    number-of-intervening-jobs (integer(0:2**31 - 1))........53
         4.3.14    job-message-from-operator (text).........................53
         4.3.15    job-k-octets-processed (integer(0:2**31 - 1))............54
         4.3.16    job-impressions-completed  (integer(0:2**31 - 1))........54
         4.3.17    job-media-sheets-completed (integer(0:2**31 - 1))........54
         4.4  Document Attributes...........................................54
         4.4.1     document-name (name).....................................54
         4.4.2     document-format (type2 enum).............................55
         4.4.3     document-uri (uri).......................................55
         4.5  Printer Description Attributes................................55
         4.5.1     printer-uri (uri)........................................56
         4.5.2     printer-uri-user (uri)...................................57
         4.5.3     printer-name (name)......................................57
         4.5.4     printer-location (text)..................................57
         4.5.5     printer-description (text)...............................57
         4.5.6     printer-more-info-site (uri).............................57
         4.5.7     printer-driver-installer (uri)...........................57
         
         
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         4.5.8     printer-make-and-model (text)............................57
         4.5.9     printer-more-info-manufacturer (uri).....................58
         4.5.10    printer-state (type1 keyword)............................58
         4.5.11    printer-state-reasons (1setOf type2 keyword).............59
         4.5.12    printer-is-accepting-jobs (boolean)......................61
         4.5.13    printer-state-message (text).............................61
         4.5.14    queued-job-count (integer(0:2**31 - 1))..................61
         4.5.15    printer-message-from-the-operator (text).................61
         4.5.16    printer-locale (locale)..................................61
         4.5.17    printer-locales-supported (1setOf locale)................61
         4.5.18    color-supported (boolean)................................61
         4.5.19    pdl-override (type2 keyword).............................62
         4.5.20    Security Related Attributes..............................63
         4.5.20.1       message-protection-supported (keyword)..............63
         4.5.20.2       authentication-authorization-supported (keyword)....63
         5.   Conformance...................................................64
         5.1  Conditionally Mandatory.......................................64
         5.2  Client Conformance Requirements...............................64
         5.3  Printer Object Conformance Requirements.......................65
         5.3.1     Objects..................................................65
         5.3.2     Operations...............................................65
         5.3.3     Attributes...............................................65
         5.3.4     Printer extensions.......................................66
         5.3.5     Attribute Syntaxes.......................................66
         5.4  Security Conformance Requirements.............................66
         6.   IANA Considerations (registered and private extensions).......66
         6.1  Typed Extensions..............................................67
         6.1.1     Type1....................................................67
         6.1.2     Type2....................................................67
         6.1.3     Type3....................................................68
         6.1.4     Type4....................................................68
         6.2  Registration of MIME types/sub-types for document-formats.....68
         7.   Security Considerations.......................................69
         8.   References....................................................69
         9.   Author's Address..............................................70
         10.  APPENDIX A: Terminology.......................................73
         10.1 Conformance Terminology.......................................73
         10.1.1    MUST.....................................................73
         10.1.2    MUST NOT.................................................73
         10.1.3    SHOULD...................................................73
         10.1.4    SHOULD NOT...............................................73
         10.1.5    MAY......................................................73
         10.1.6    CONDITIONALLY MANDATORY..................................74
         10.1.7    NEED NOT.................................................74
         10.2 Model Terminology.............................................74
         10.2.1    Keyword..................................................74
         10.2.2    Parameters...............................................74
         10.2.2.1       Parameter Name......................................74
         
         
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         10.2.2.2       Parameter Value.....................................75
         10.2.2.3       Parameter Syntax....................................75
         10.2.3    Attributes...............................................75
         10.2.3.1       Attribute Name......................................75
         10.2.3.2       Attribute Group Name................................76
         10.2.3.3       Attribute Value.....................................76
         10.2.3.4       Attribute Syntax....................................76
         10.2.4    Supports.................................................76
         11.  APPENDIX B:  Status Codes.....................................77
         11.1 Status Codes (type2 keyword)..................................78
         11.1.1    Informational............................................78
         11.1.2    Successful Status Codes..................................78
         11.1.2.1       successful-ok.......................................78
         11.1.3    Redirection Status Codes.................................78
         11.1.4    Client Error Status Codes................................79
         11.1.4.1       client-error-bad-request............................79
         11.1.4.2       client-error-forbidden..............................79
         11.1.4.3       client-error-not-authenticated......................79
         11.1.4.4       client-error-not-authorized.........................79
         11.1.4.5       client-error-not-possible...........................80
         11.1.4.6       client-error-timeout................................80
         11.1.4.7       client-error-not-found..............................80
         11.1.4.8       client-error-gone...................................80
         11.1.4.9       client-error-request-entity-too-large...............81
         11.1.4.10      client-error-request-URI-too-long...................81
         11.1.4.11      client-error-unsupported-document-format............81
         11.1.4.12      client-error-attribute- not-supported...............81
         11.1.5    Server Error Status Codes................................82
         11.1.5.1       server-error-internal- error........................82
         11.1.5.2       server-error-operation-not-supported................82
         11.1.5.3       server-error-service-unavailable....................82
         11.1.5.4       server-error- version-not-supported.................82
         11.1.5.5       server-error-device-error...........................83
         11.1.5.6       server-error-temporary-error........................83
         11.2 Status Keywords for IPP Operations............................84
         12.  APPENDIX C: "document-format" enum values.....................84
         13.  APPENDIX D:  "media" keyword values...........................87
         
         
         
         
         
         
         
         
         
         
         
         
         
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         1. Simplified Printing Model
         
         In order to a achieve its goal of realizing a workable printing
         protocol for the Internet, the Internet Printing Protocol (IPP) is
         based on a simplified printing model which abstracts the many (often
         complex) components of real world printing solutions.  Many of these
         systems include features, interfaces, and relationships that are
         beyond the scope of IPP.  IPP has to run in a distributed computing
         environment where requesters of print services  (clients,
         applications, PC drivers, etc.) cooperate and interact with print
         service providers.  Although the underlying configuration may be a
         complex n-tier client/server system, an important simplifying step in
         the IPP model is to expose only the key objects and interfaces
         required for printing.  The IPP model encapsulates these important
         elements into three simple object types:
         
           Printer (Section 2.1)
           Job (Section 2.2)
           Document (Section 2.3)
         
         Each object type has an associated set of operations (see section 3)
         and attributes (see section 4)
         
         It is important, however, to understand that in real system
         implementations (which lie underneath the abstracted IPP model), there
         are other components of a print service which are not explicitly
         defined in the IPP model. The following figure illustrates where IPP
         fits with respect to these other components.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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                                      +--------------+
                                      |  Application |
                            o         +. . . . . . . |
                           \|/        |   Spooler    |
                           / \        +. . . . . . . |   +---------+
                         End-User     | Print Driver |---|  File   |
               +-----------+ +-----+  +------+-------+   +----+----+
               |  Browser  | | GUI |         |                |
               +-----+-----+ +--+--+         |                |
                     |          |            |                |
                     |      +---+------------+---+            |
         N   D   S   |      |      IPP Client    |------------+
         O   I   E   |      +---------+----------+
         T   R   C   |                |
         I   E   U   |
         F   C   R   -------------- Transport ------------------
         I   T   I
         C   O   T                    |         --+
         A   R   Y           +--------+--------+  |
         T   Y               |    IPP Server   |  |
         I                   +--------+--------+  |
         O                            |           |
         N                   +-----------------+  | IPP Printer
                             |  Print Service  |  |
                             +-----------------+  |
                                      |         --+
                             +-----------------+
                             | Output Device(s)|
                             +-----------------+
         
         IPP Printers encapsulate the functions normally associated with
         physical output devices along with the spooling, scheduling and
         multiple device management functions associated with a print server.
         Printers may be registered as entries in a directory where end users
         find and select them based on some sort of filtered and context based
         searching.  The directory is used to store relatively static
         information about the Printer, allowing end users to search for and
         find Printers that match their search criteria (name, context, printer
         capabilities, etc.).
         
         IPP clients implement the IPP protocol on the client side and give end
         users or programs the ability to query an IPP Printer and submit and
         manage their print jobs.  An IPP server is just that part of the IPP
         Printer that implements the protocol.  The rest of the IPP Printer
         implements the application semantics of the print service itself.  The
         IPP Printer may be embedded in an output device or may be implemented
         on a host on the network that communicates with the output device.
         
         
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         All information about the Printer, both static and dynamic
         information, can be accessed directly from the Printer itself.  The
         more dynamic information associated with a Printer includes state,
         currently loaded and ready media, number of jobs on the Printer,
         errors, warnings, etc.  The Printer is optionally represented by an
         entry in a directory service.  The more static information (name, URI,
         location, etc.) are stored with along with the entry in the directory
         service to enable filtered directory queries.
         
         When a job is submitted to the Printer, the Printer SHALL create a Job
         object.  The end user then interacts with this new Job to query its
         status and monitor the progress of the job.  End users may also cancel
         the Job.  The end user is able to register to receive certain events
         which are then routed using the notification service(s).
         
         
         2. IPP Objects
         
         The IPP model introduces objects of type Printer, Job, and Document.
         Each object type is defined as a set of possible attributes that may
         be supported by each instance of an object of that type.  The
         attributes (and values) supported by each object instance describe the
         implementation (that is the realizable features, functions, and
         characteristics either in software or hardware) for that object
         instance.  For example, the object type "Printer" is defined as set of
         attributes that each instance of a Printer object might potentially
         support.  In the same manner, the object type "Job" is defined as a
         set of attributes that are potentially supported by each instance of a
         Job object.
         
         Each attribute included in the set of attributes defining an object
         type labeled as:
         
           "MANDATORY": each object instance MUST support the attribute.
           "OPTIONAL": each object instance MAY support the attribute.
           "CONDITIONALLY MANDATORY": whether or not the object instance
              supports the attribute is determined by a semantic condition.
              For example, if the implementation behind a given instance of a
              Printer object knows about and is able to support multiple levels
              of job priorities, that instance MUST support the "job-priority-
              supported" attribute.  An administrator may set the values to be
              somewhat more restrictive that what a given implementation might
              allow, however the attribute MUST still be supported.
         
         
         
         
         
         
         
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         2.1 Printer Object
         
         A major component of the IPP model is the Printer object.  The
         capabilities and state of an IPP Printer are described by its
         attributes.  Printer attributes are grouped as follows:
         
           "job-template" attributes (section 4.2)
           "printer-description" attributes (section 4.5)
         
         Operations which are invoked on a printer include:
         
           Get-Operations (Section 3.1.1)
           Print-Job (section 3.1.2)
           Print-URI (Section 3.1.3)
           Validate-Job (Section 3.1.4)
           Create-Job (section 3.1.5)
           Get-Attributes (section 3.1.9)
           Get-Jobs (section 3.1.10)
         
         An instance of a Printer object implements the IPP protocol.  Using
         the protocol, end users may query the attributes of the Printer,
         submit jobs to the Printer, determine subsequent states of submitted
         and queued jobs, and cancel their own print jobs.  The actual
         implementation components behind the Printer object abstraction may
         take on different forms and different configurations, however, the
         details of the configuration of real components are transparent to the
         end user.
         
         Since a Printer object is an abstraction of a generic document output
         device and print service provider, an IPP Printer object could be used
         to represent any real or virtual device with semantics consistent with
         the Printer object. For example, an instance of a Printer object could
         be used to front end a fax-out device, any kind of imager, or even a
         CD writer.
         
         Some examples of configurations supporting a Printer object include:
         
           1) An output device, with no spooling capabilities
           2) An output device, with a built-in spooler
           3) A print server supporting IPP with one or more associated output
              devices
              3a) The associated output devices might or might not be capable
                of spooling jobs
              3b) The associated output devices might or might not support IPP
         
         See the following figures for some examples on how to view Printer
         objects on top of several print system configurations.  The embedded
         
         
         
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         case below represents configurations 1 and 2. The hosted and fan-out
         figures below represent configuration 3.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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         Legend:
         
         ##### indicates a Printer object which is
               either embedded in an output device or is
               hosted in a server.  The implementation
               might or might not be capable of queuing/spooling.
         
         any   indicates any network protocol or direct
               connect, including IPP
         
         
         embedded printer:
                                                   output device
                                                 +---------------+
          O   +--------+                         |  ###########  |
         /|\  | client |------------IPP------------># Printer #  |
         / \  +--------+                         |  # Object  #  |
                                                 |  ###########  |
                                                 +---------------+
         
         
         hosted printer:
                                                 +---------------+
          O   +--------+        ###########      |               |
         /|\  | client |--IPP--># Printer #-any->| output device |
         / \  +--------+        # Object  #      |               |
                                ###########      +---------------+
         
         
         
                                                  +---------------+
         fan out:                                 |               |
                                              +-->| output device |
                                          any/    |               |
          O   +--------+      ###########   /     +---------------+
         /|\  | client |-IPP-># Printer #--*
         / \  +--------+      # Object  #   \     +---------------+
                              ########### any\    |               |
                                              +-->| output device |
                                                  |               |
                                                  +---------------+
         
         
         
         2.2 Job Object
         
         A Job object is used to model a job.  A job can contain one or more
         documents.  The information required to create a Job object is sent in
         
         
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         a create request from the end user via an IPP client to a Printer.  A
         create request can be either a Print-Job Request, a Print-URI Request,
         or a Create-Job Request.  The Printer MUST perform validation checks
         to verify that the job may indeed be processed.  A client MAY send a
         Validate-Job Request (with no document data) so that the Printer
         performs all validation checks without the overhead of transferring
         all of the document data.  As an example of some of the validation
         checks that are performed, the create request may specify that the
         documents within the job are to be printed duplex (on both sides of
         the media).  However, the Printer might not support such a feature.
         Once the Printer validates the submitted information, a Job object is
         created.  The instance of the Job object is initialized with
         information from the create request.  If a Create-Job operation is
         used to create the Job object, subsequent Send-Document operations are
         used to transfer the document data from the client to the IPP Printer.
         
         This model specification defines rules for what is done when:
         
           - optional attributes are missing
           - there are conflicts between what is supported and what is
              requested
           - there are conflicts between what the client requests via external
              attributes in the IPP operation and what the client requests in
              embedded instructions in the document page description language
              (PDL).
         
         Job attributes are grouped as follows:
         
           "job-template" attributes (optionally supplied by the client/end
              user, section 4.2)
           "job-description" attributes (set by the Printer, section 4.3)
         
         The following operations can be invoked on Jobs:
         
           Send-Document (section 3.1.6)
           Send-URI (Section 3.1.7)
           Cancel Job (section 3.1.8)
           Get-Attributes (section 3.1.9)
         
         
         2.3 Document Object
         
         A Document object consists of either printable data or a reference
         (URI) to printable data and a set of Document Attributes (see section
         4.4).  These Document Attributes only describe the data to be printed;
         they do not include any specialized document processing instructions
         that apply to only this one Document. All Job Template attributes,
         that isthose attributes that describe desired job processing behavior,
         
         
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         are defined as part of the Job object, therefore, they apply equally
         to all Documents within a Job.
         
         Currently there are no operations defined for Document objects.
         
         
         2.4 Object Relationships
         
         Instances of objects within the system have relationships that MUST be
         maintained persistently along with the persistent storage of the
         object attributes.  An instance of a Printer object usually represents
         one or more output devices.  A Printer object may represent a logical
         device which "processes" jobs but never actually uses a physical
         output device to put marks on paper (for example a Web page publisher
         or an interface into an online document archive or repository).  A
         Printer can contain zero or more Job objects.  An instance of a Job
         object is contained in exactly one Printer object (the same document
         data could be sent to a the same or a different Printer, but the
         corresponding Job object would be an identical, but different Job
         object).  A Job object contains one or more Documents.  If the
         Document is simply a reference to some print data stream, the
         reference may be used in multiple Documents in the same Job or even in
         different Jobs.  If the Document is not just a reference, but an
         actual stream of print data, the stream is contained in only one
         Document, although there can be copies of the same document data in
         other Documents in the same or different Jobs.
         
         
         2.5 Object Identity
         
         All instances of Printer and Job objects have a URI so that they can
         persistently and unambiguously referenced.  The IPP model requires
         that these values be URIs as defined by RFC 1738 [11] and RFC 1808.
         In addition to an identifier attribute, instances of Printer and Job
         objects may have a name.  An object name need not be unique across all
         instances of all objects. The Printer name is chosen and set by an
         administrator. If not supplied by the client, the Printer creates the
         Job name.  In all cases, the name only has local meaning, and it is
         not constrained to be unique.
         
         To summarize, each instance of Printer and Job objects will have two
         identifying attributes:
         
           - "xxx-uri": The unique identifier for this object instance
           - "xxx-name": The non unique name for this object instance
         
         Document objects sent to an IPP Printer only have names, no
         identifiers.  The "document-name" attribute is used to store the name
         
         
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         of the Document.  This name is just of interest within the context of
         a Job; it need not be unique.
         
         If Documents are printed by reference, the corresponding document
         object contains a "document-uri" attribute, but the value of this
         attribute is a reference to the document data to be printed; it is not
         the unique identifier of the Document object itself.
         
         
         3. IPP Operations
         
         Jobs and Printers each have a set of associated operations. End users
         or programs invoke these operations using an IPP client. The
         operations are:
         
           For a Printer object:
              Get-Operations (section 3.1.1) Print-Job (section 3.1.2) Print-
                URI (section 3.1.3)
              Validate-Job (section 3.1.4)
              Create-Job (section 3.1.5)
              Get-Jobs (section 3.1.8)
              Get-Attributes (section 3.1.9)
         
           For a Job object:
              Send-Document (section 3.1.6)
              Send-URI (section 3.1.7)
              Cancel-Job (section 3.1.8)
              Get-Attributes (section 3.1.9)
         
         When a client communicates with a remote IPP object, it sends an
         operation request to the URI for that object.  Each request carries
         along with it the input parameters and data required to perform the
         specified operation.  Each request requires a response from the object
         indicating success or failure of the operation including output
         parameters, status codes, and/or status messages. The representation
         and encoding of the IPP protocol are contained in "Internet Printing
         Protocol: Protocol Specification."[23]
         
         It is assumed that URIs for IPP Printers are available to end users or
         programs that wish to invoke Printer operations.  Although NOT
         MANDATORY, it is RECOMMENDED that Printers be registered in a
         directory service which end users and programs can interrogate.
         "Internet Printing Protocol: Directory Schema"[24] defines the
         attributes to be associated with a Printer entry in a directory
         service.
         
         
         
         
         
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         3.1 Operation Semantics
         
         In this section, the IPP operations are described in terms of their
         contents and semantics including both the request and the response for
         each operation.
         
         In order to create a new Job object, a client uses one of three
         operations:
         
           - The Print-Job operation: This operation is used if the client
              wants to create a Job with only a single Document and the
              document data is included in the request.  In this case, the
              client "pushes" the document data to the Printer.
         
           - The Print-URI operation: This operation is used if the client
              wants to create a Job with only a single Document and only a URI
              reference to the document data (not the document data itself) is
              included in the request.  In this case, the Printer "pulls" the
              document data from the location identified by the URI.
         
           - The Create-Job operation: This operation is used if the client
              wants to create a Job with one or more Documents.  This operation
              is followed by an arbitrary number of Send-Document or Send-URI
              operations (each creating another Document for this Job).  The
              Send-Document operation includes the document data with the
              operation request (client "pushes" the document data to the
              printer), and the Send-URI operation includes only a reference (a
              URI) to the document data (the Printer "pulls" the document data
              from the referenced location).
         
         A Create-Job operation followed by a only one Send-Document operation
         is semantically equivalent to a Print-Job operation, however, for
         performance reasons, the client SHOULD use the Print-Job operation for
         all single Document Jobs.  Throughout this model specification, the
         term "create request" is used to refer to any of these three operation
         requests.
         
         Every operation response returns a MANDATORY status code and an
         OPTIONAL status message (see Section 10).  In most cases, if the
         status code indicates an error (the code belongs to either the
         "client-error" or the "server-error" group), there are additional
         output parameters returned that are not returned in the successful
         case.
         
         In many of these operations, a client supplies a list of attributes to
         be returned in the response.  A Printer may be configured, for
         security reasons, not to return all attributes that a client requests.
         It may even return none of the requested attributes.  In such cases,
         
         
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         the status returned is the same as if the Printer had returned all
         requested attributes.  The client cannot tell by such a response
         whether the requested attribute was present or absent on the Printer.
         
         3.1.1 Get-Operations Operation
         
         Since some of the IPP operations defined in this specification are
         OPTIONAL and therefore some implementations may choose to not
         implement support them, this operation is a simple, MANDATORY
         operation that all implementations MUST support.  The client uses this
         operation to query a specific implementation for a list of supported
         operations.
         
         3.1.1.1 Get-Operations Request
         
         The Get-Operations Request has no input parameters.
         
         3.1.1.2 Get-Operations Response
         
         The Printer returns the following output parameters as part of the
         Get-Operations Response:
         
           Supported Operations ("supported-operations"):
              A list of the operations that this implementation supports
                (including all MANDATORY operations).  The values are taken
                from the following set: 'Get-Operations', 'Print-Job', 'Print-
                URI', 'Validate-Job', 'Create-Job', 'Get-Jobs', 'Get-
                Attributes', 'Send-Document', 'Send-URI', and 'Cancel-Job'.
         
              Note: Since this list contains all MANDATORY operations ('Get-
              Operations', 'Print-Job', 'Validate-Job', 'Get-Jobs', 'Get-
              Attributes', and 'Cancel-Job'), this output parameter will never
              be empty.
         
         
         
         
         3.1.2 Print-Job Operation
         
         When an end user desires to submit a print job with only one Document,
         the client sends a Print-Job Request to a Printer and receives a
         Print-Job Response from that Printer.  The information in a Print-Job
         Request (along with any default information associated with the
         Printer) is sufficient for the Printer to create a Job object and then
         process that Job.  A Print-Job operation differs from a Print-URI
         operation in that a Print-Job operation contains the document data to
         be printed and a Print-URI operation only contains a reference to the
         document data.
         
         
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         3.1.2.1 Print-Job Request
         
         The following input parameters are part of the Print-Job Request:
         
           Job Template Attributes:
              An optional set of Job Template attributes as defined in section
              4.2.  If the client supplies no Job Template attributes in the
              Create-Job Request, the Printer uses its default value attributes
              when processing the job.  Since a Print-Job operation is used for
              a Job with only one Document, the Document attributes "document-
              name" and "document-format" are also supplied by the client.
              "document-name" is MANDATORY; "document-format" is OPTIONAL.
         
           Document Content:
              The client supplies the document data to be processed.
         
         The simplest Print-Job Request consists of just the Document Content
         and nothing else.  In this case, the Printer creates a new Job object
         with no associated Job Template attributes and the job contains a
         single Document.
         
         When a Printer receives a Print-Job Request, the Printer either
         accepts or rejects the request. The Printer accepts the Print-Job
         Request and creates a Job object if it is able to accept all Job
         Template attributes in the request.  The Printer rejects the request
         and does not create a Job object if the Printer rejects any Job
         Template attribute in the request.  There are six cases to consider
         when accepting or rejecting Job Template attributes:
         
           1. The client supplies a Job Template attribute named "xxx" and the
              value supplied by the client is among the values supported by the
              Printer (i.e., is among the values of the Printer's "xxx-
              supported" attribute): The "xxx" Job Template attribute is
              accepted. The Printer creates the Job object and associates the
              "xxx" attribute with the new Job object using  the value supplied
              by the client.
         
           2. The client supplies a Job Template attribute but the attribute
              is syntactically bad: The Printer SHALL reject the job and return
              name of the badly formed attribute (if known) in the
              "unsupported-attributes" response parameter.
         
           3. The client supplies a Job Template attribute and the attribute
              value is not among the values supported by the Printer:  This
              case depending on the value of the "best-effort' attribute (see
              Section 4.2.8), tIf the client supplies a "best-effort" of
              'false' (or supplies no "best-effort" attribute and the Printer's
              default behavior attribute is set to 'false') the Printer SHALL
         
         
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              reject the Job and return the 'client-error-attribute-
              unsupported" error code and the unsupported attribute in the
              "unsupported-attributes " output parameter. If the client
              supplies a "best-effort" of 'true' (or supplies no "best-effort"
              attribute and the Printer's default behavior attribute is set to
              'true') the Printer SHALL accept the Job and substitute supported
              values for all unsupported values supplied by the client.  In
              this case, if everything else is ok, the Printer returns a
              "successful-ok" status code.  The client must query the newly
              create Job object to find out if any of the requested values have
              been modified.
         
           4. The client supplies a Job Template attribute and the Printer
              does not support the attribute: The Printer rejects the
              attribute.  The Printer returns the 'client-error-attribute-
              unsupported' error code and the  rejected attribute in the
              "unsupported-attributes" output parameter.
         
           5. The client does not supply a Job Template attribute, but the
              Printer supports the attribute:  The attribute is accepted and
              when the Printer creates the Job object, the Printer SHALL NOT
              associate the attribute with the new  Job object using Printer's
              default value attribute.  When the Printer processes that Job,
              the Printer uses the behavior implied by the default value
              Printer attribute as set at the time of Job processing (not Job
              creation).  In other words, these rules allow for a Job object to
              be created without implementing some of the Job Template
              attributes.  As the Printer processes the Job, if the Printer
              supports a corresponding default value attribute for the missing
              Job Template attribute, the Printer uses the default value.
         
           6. The client does not supply an attribute, and the Printer does
              not support the attribute:  The Printer accepts the Job. However,
              as far as IPP is concerned, the result of processing that Job
              (with respect to the missing attributes) is undefined.  In many
              cases though, this case represents a legacy environment, and even
              without IPP attributes, the job will be processed successfully.
              For example, the document data might have been generated by a
              device-specific printer driver that formats the job and emits a
              data stream (a stream of PDL) that is finely tuned for the
              intended output device and its internal interpreter. But, both
              the output device and the printer driver are unaware of the IPP
              protocol, and an intermediate process (which is IPP aware) is
              able to submit the job and make sure that it is delivered to the
              output device, yet not be aware of all the Job Template
              attributes that might possibly be supported.
         
         
         
         
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         3.1.2.2 Print-Job Response
         
         The Printer SHALL return to the client the following output parameters
         as part of the Print-Job Response:
         
           Job Identifier ("job-uri"):
              A URI which the client SHALL use for all other operations on this
              Job
         
           Job Status Attributes:
              This includes the following Job attributes:  "job-name", "job-
              state", and "job-state-reasons".  The value of each attribute is
              taken from a "snapshot" of the new Job object sometime after the
              time the Printer receives the print request until just prior to
              returning the response to the client.  Since the  "job-state-
              message" attribute is OPTIONAL, it MAY be included in the
              response, but it is NOT REQUIRED.
         
              Note: Since any printer state information which affects a job's
              state is reflected in the "job-state" and "job-state-reasons"
              attributes, it is sufficient to return only these attributes and
              no specific printer status attributes.
         
           Unsupported Attributes:
              If there is an error, this output parameter contains a set of
              attributes that are unsupported.  This output parameter is not
              used if the status code indicates that there were no errors.
         
         
         
         
         
         
         The simplest response consists of the just the job identifier ("job-
         uri") and Job Status attributes output parameters with a status code
         of "successful-ok".
         
         3.1.3 Print-URI Operation
         
         This operation is identical to the Print-Job operation (section 3.1.2)
         except that a client supplies a reference (a URI) to the document data
         to be printed rather than the document data itself.  It is up to the
         IPP server to interpret the URI and subsequently "pull" the document
         from the source referenced by the URI string.
         
         3.1.3.1 Print-URI Request
         
         The following elements are part of the Print-URI Request:
         
         
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           Job Template Attributes:
              (see section 3.1.2.1)
         
           Document URI ("document-uri"):
              The client supplies a URI reference to the document data rather
              than the document data itself.
         
         
         
         3.1.3.2 Print-URI Response
         
         The Printer SHALL return to the client the following output parameters
         as part of the Print-URI Response:
         
           Job Identifier ("job-uri"):
              (see section 3.1.2.2)
         
           Job Status:
              (see section 3.1.2.2)
         
           Unsupported Attributes:
              (see section 3.1.2.2)
         
         
         
         3.1.4 Validate-Job Operation
         
         This operation is identical to the Print-Job operation (section 3.1.2)
         except that a client supplies no document data or any reference to
         document data and the Printer allocates no resources (i.e., a new Job
         object) to process the job. The VALIDATE request is only used to
         verify capabilities of a printer object against whatever input
         parameters are supplied in the Validate-Job request.
         
         3.1.4.1 Validate-Job Request
         
         The following elements are part of the Validate-Job Request:
         
           Job Template Attributes:
              (see section 3.1.2.1)
         
         
         
         3.1.4.2 Validate-Job Response
         
         The Printer SHALL return to the client the following output parameters
         as part of the Validate-Job Response:
         
         
         
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           Unsupported Attributes:
              (see section 3.1.2.2)
         
         
         Note: In this case, no "job-uri" or Job Status output parameters are
         returned.
         
         
         
         3.1.5 Create-Job Operation
         
         This operation is similar to the Print-Job operation (section 3.1.2)
         except that a client supplies no document data or any reference to
         document data in the Create-Job request.  This operation is followed
         by one or more Send-Document or Send-URI operations.  It is possible
         for a given implementation to only support either Send-Document or
         Send-URI but not both.  In that case, a client SHOULD NOT use an
         unsupported operation.  If a Printer supports the Create-Job
         operation, it MUST also support one of the Send-Document or Send-URI
         operations or both.
         
         3.1.5.1 Create-Job Request
         
         The following elements are part of the Create-Job Request:
         
           Job Template Attributes:
              (see section 3.1.2.1)
         
         
         
         3.1.5.2 Create Job Response
         
         The Printer returns to the client the following output parameters as
         part of the Create-Job Response:
         
           Job Identifier ("job-uri"):
              (see section 3.1.2.2)
         
           Job Status:
              (see section 3.1.2.2)
         
         
           Unsupported Attributes:
              (see section 3.1.2.2)
         
         
         
         
         
         
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         3.1.6 Send-Document Operation
         
         Once a Job object has been created using a Create-Job operation
         (returning a "job-uri"), a client directs a Send-Document operation to
         the newly create Job object.  The operation adds a new Document to the
         Job object. An entire document MUST be sent in a single Send-Document
         operation.
         
         3.1.6.1 Send-Document Request
         
         The client submits the request to a Job URI.
         
         The following abstract data types are part of the Send-Document
         Request:
         
           Document Attributes:
              A set of Document Description attributes (section 4.4).
         
           Last Document Flag ("last-document"):
              This is a boolean flag that is set to 'true' if this is the last
              Document for the Job.
         
           Document Content:
              The client supplies the document data.
         
         
         3.1.6.2 Send-Document Response
         
         The following output parameters are part of the Send-Document
         Response:
         
           Job Status:
              (see section 3.1.2.2)
         
         
           Unsupported Attributes:
              (see section 3.1.2.2)
         
         
         3.1.7 Send-URI Operation
         
         This operation is identical to the Send-Document operation (see
         section 3.1.6) except that a client supplies a reference (a URI) to
         the document data to be printed rather than the document data itself.
         It is up to the IPP server to interpret the URI and subsequently
         "pull" the document from the source referenced by the URI string.
         
         
         
         
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         3.1.7.1 Send-URI Request
         
         The client submits the request to a Job URI.
         
         The following abstract data types are part of the Send-URI Request:
         
           Document Attributes:
              (see section 3.1.6.1)
         
           Last Document Flag ("last-document"):
              (see section 3.1.6.1)
         
           Document Reference ("document-uri"):
              The client supplies a URI reference to the document data.
         
         
         3.1.7.2 Send-URI Response
         
         The following output parameters are part of the Send-URI Response:
         
           Job Status:
              (see section 3.1.6.2)
         
           Unsupported Attributes:
              (see section 3.1.6.2)
         
         
         3.1.8 Cancel Job Operation
         
         This operation allows a user to cancel one specific Print Job any time
         after the print job has been established on the Printer.  Some pages
         may be printed before a job is terminated if printing has already
         started when the Cancel Job operation is received.  Only the end user
         who is also the job originator ("job-originating-user" Job attribute)
         can cancel the job using IPP 1.0.
         
         3.1.8.1 Cancel-Job Request
         
         The client submits the request to a Job URI.
         
         The following abstract data types are part of the Cancel Job Request:
         
           Message ("message"):
              Optional message to the operator
         
         
         
         
         
         
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         3.1.8.2 Cancel-Job Response
         
         There are no output parameters other Cancel Job Response other than
         the Status Code and optional Status Message.
         
         
         
         
         3.1.9 Get-Attributes Operation
         
         The Get-Attributes operation allows a client to obtain information
         from a Printer or Job object. The client supplies as an operation
         parameter the set of attribute names and/or attribute group names that
         the requester is interested in.  The Printer returns a corresponding
         attribute set in the response with the appropriate attribute values
         filled in for each requested attribute (either explicitly named in the
         request or implicitly included by naming an attribute group).
         
         3.1.9.1 Get-Attributes Request
         
         When querying a Printer object, the client submits the Get-Attributes
         request to a Printer URI.  When querying a Job object, the client
         submits the Get-Attributes request to a Job URI.The following input
         parameters are part of the Get-Attributes Request whether or not the
         request is to a Printer URI or a Job URI:
         
           Requested Attributes ("requested-attributes") :
              An optional set of attribute names (without values) or attribute
              group names in whose values the requester is interested.  If the
              client omits this input parameter, the Printer SHALL respond as
              if this input parameter had been supplied with a value of 'all'.
         
              Attributes may be requested by name or by group name.  For Jobs,
              the attribute groups include:
         
              - 'job-template': all of the Job Template attributes that apply
                to a Job object (the first column of the table in Section
                4.2).
              - 'job-description': the Job Description attributes in Section
                4.3.
         
              For Printers, the attribute groups include:
         
              - 'job-template': all of the Job Template attributes that apply
                to a Printer object (the last two columns of the table in
                Section 4.2).
              - 'printer-description': the attributes specified in Section 4.5.
         
         
         
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              There are also special groups:
         
              - 'none': no attributes of the specified object.  'none' is
                primarily useful in Get-Jobs, but can be used as a "ping" with
                the Get-Attributes operation.
              - 'all': all supported attributes
         
              It is NOT REQUIRED that a Printer support ALL attributes
              belonging to a group, however it is MANDATORY that a Printer
              implementation understand these group names.
         
              Document Attributes ("document-name", "document-format", and
              "document-uri", see Section 4.4) may also be requested either
              individually or as a group named 'document-attributes'.  If any
              or all of these attributes are requested, in the response, they
              are treated as multi-valued attributes (one value for each
              Document in the Job).  If there are 5 Documents in the Job, then
              each returned Document attribute MUST have 5 values: the set of
              first values from each attribute correspond to the first
              Document, the set of second values correspond to the second
              Document, and so on.  In order to maintain the same number of
              values in each returned attribute, if there is no value for the
              "document-format" attribute for one of the Documents, the value
              'other' is returned in its place, and if there is no value for
              the "document-uri" attribute for one of the Documents, the
              special URI 'none' is returned in its place.  For example if all
              Document attributes are requested, and there are 3 Documents is a
              Job, the returned attributes might look like:
         
              document-name = 'Document 1', 'Document 2', Document 3'
              document-format = 'langPS', 'other', 'langPCL'
              document-uri = ' ftp://some.domain.com/file1.ps', 'none', 'none'
         The following input parameters are part of the Get-Attributes Request
         only when querying a Printer:
         
           Document Format ("document-format") :
         
              This input parameter conditions the Printer attributes and values
              that might depend on the document format.  The Printer SHALL
              return only (1) those attributes that are supported and (2) the
              attribute values that are supported for the specified document
              format.  By specifying the document format, the client can
              eliminate the attributes and values that are not supported for a
              specific document format.  For example, a Printer might have
              multiple interpreters to support both 'langPS' (for PostScript)
              and 'langPCL' (for PCL) documents.  However, for only one of
              those interpreters might the Printer be able to support "number-
              up" with values of 'one', 'two', and 'four'.  For the other
         
         
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              interpreter it might be able to only support "number-up" with a
              value of 'one'.
         
              If the client omits this input parameter, the Printer SHALL
              respond as if the input parameter had been set to the value of
              the Printer's default value "document-format" attribute were
              supplied.  It is recommended that the client always supply a
              value for document-format, since the Printer's default value for
              document-format may be 'langAutomatic', in which case the
              returned attributes and values are for the union of the document
              formats that the Printer can automatically sense.
         
              If this input parameter is sent in a Get-Attribute Request sent
              to a Job URI, the request is rejected with a status code of
              'client-error-not-possible'.
         
         
         
         3.1.9.2 Get-Attributes Response
         
         The Printer returns the following response parameters as part of the
         Get-Attributes Response:
         
           Requested Attributes:
              This is a the set of requested attributes and their current
              values.  The Printer ignores (does not respond with) any
              requested attribute which is not supported.
         
         
         
         
         
         
         3.1.10 Get-Jobs Operation
         
         The Get-Jobs operation allows a client to retrieve list of Jobs
         belonging to the target Printer object.  The client may also supply a
         list of Job attribute names or attribute group names.  These Job
         attributes will be returned for each Job that is returned.
         
         This operation is like Get-Attributes, except that Get-Jobs operation
         returns attributes from more than one object.
         
         3.1.10.1 Get-Jobs Request
         
         The client submits the Get-Jobs request to a Printer URI.
         
         The following input parameters are part of the Get-Jobs Request:
         
         
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           Limit ("limit"):
              This is an integer value that indicates a limit to the number of
              Jobs returned.  The limit is a "stateless limit" in that if the
              limit is n then only the first n jobs are returned in the Get-
              Jobs Response; there is no mechanism to allow for the "next" n
              jobs.  The limit applies across all Job States requested.  For
              example, if the limit if 50, and there are 75 jobs in the
              'completed' state and 25 in the 'pending state' and the client
              requests first 'completed jobs' and then 'pending' jobs, only the
              oldest 50 'completed' jobs are returned.  The other 25
              'completed' jobs are not returned and neither are any of the
              'pending' jobs returned.
         
           Requested Job Attributes ("requested-attributes"):
              An optional set of Job attribute names or attribute groups names
              in whose values the requester is interested.  This set of
              attributes is returned for each Job that is returned..  The
              attribute group names are the same as for the Get-Attributes
              operation for the Job object.  If the client omits this input
              parameter, the Printer SHALL respond as if this input parameter
              had been supplied with a value of " 'job-uri'.
         
         3.1.10.2 Get-Jobs Response
         
         The Printer SHALL return the following output parameters as part of
         the Get-Jobs Response:
         
           Req     uested Attributes:
              The result includes zero or more Job objects each with zero or
              more attributes.  Jobs are returned in the following order: First
              all active Jobs (Jobs in the 'pending', 'processing', 'pending-
              held', and 'processing-stopped' states) are returned oldest to
              newest (with respect to expected completion time) followed by all
              completed Jobs (Jobs in the 'completed', 'aborted', or 'canceled'
              states) newest to oldest (with respect to actual completion
              time).  Jobs that are in the 'pending-held' state SHALL appear in
              their position as if they were 'pending' (otherwise, a user might
              be confused by Jobs that move from 'pending-held' to 'pending' as
              seeming to jump ahead in the queue).
         
         
         
         
         
         3.2 Operation Status Codes and Messages
         
         An operation status code provides information on the processing of a
         request.  A message provides a short textual description of the status
         
         
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         of the operation.  The status code is intended for use by automata and
         a status message is intended for the human user.  An IPP application
         (i.e. a browser, GUI, print driver or gateway) is not required to
         examine or display the message.  Status codes and suggested
         corresponding status messages are described in section 11..
         
         
         4. Object Attributes
         
         This section describes the attributes with their corresponding
         syntaxes and values that are part of the IPP model. The sections below
         show the objects and their associated attributes which are included
         within the scope of this protocol.  Many of these attributes are
         derived from other relevant specifications:
         
           - ISO/IEC 10175 DPA (Final, June 1996) [5]
           - RFC 1759 Printer MIB (Proposed Standard, May 1995) [1]
           - Internet-Draft: Printer MIB (Draft Standard in progress, July
              1997) [29]
           - Internet-Draft: Job Monitoring MIB (I-D in progress, June 1997)
              [27]
         
         Each attribute is uniquely identified in this document using a
         "keyword" (see section 10.2.1).  The keyword is included in the
         section header describing that attribute. Not only are attributes
         uniquely identified with keywords, some attributes are defined to have
         a syntax which is a set of keywords.
         
         
         4.1 Attribute Syntaxes
         
         The following table shows the basic syntax types that a client and
         server SHALL be able to handle.
         
           text:  a sequence of characters, length: 0 to 4095, UTF8
              characters.  This syntax type is used for free form human
              readable text intended for human consumption.
         
           name:  a sequence of characters, length: 1 to 255, UTF8 characters.
              This syntax type is used for referencing some object or entity
              via a user-friendly string, such as a Printer name, a document
              name, a user name, or a host name.
         
           fileName:  a sequence of characters, length: 1 to 1024, UTF8
              characters.  This syntax type is used for referencing some file.
              The limit is the same as in POSIX and Microsoft NT.
         
         
         
         
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           keyword:  a sequence of characters, length: 1 to 255, containing
              only the characters ASCII lowercase letters ("a" - "z"), ASCII
              digits ("0" - "9"), hyphen ("-"), and underscore ("_").  The
              first character MUST be an ASCII lowercase letter.  This syntax
              type is used for enumerating semantic identifiers of entities in
              the abstract protocol (specified in this document).  These
              entities can be attribute names or values of attributes.  When a
              keyword is used to represent an attribute (its name), it MUST be
              unique within the full scope of IPP objects and attributes.  When
              a keyword is used to represent a value of an attribute, it MUST
              be unique just within the scope of that attribute.  That is, the
              same keyword can not be used for two different values within the
              same attribute to mean two different semantic ideas.  However,
              the same keyword can be used across two or more attributes,
              representing different semantic ideas for each attribute.
         
           enum:  an enumerated integer value that is in the range from -2**31
              to 2**31 - 1.   Each value has an associated keyword name.  Each
              attribute (whose syntax is enum) enumerates the values that are
              defined for the attribute.  The enum type is used for attributes
              for which there are enum values assigned by other standards, such
              as SNMP MIBs.  A number of attribute enum values in this
              specification are also used for corresponding attributes in the
              IETF Printer MIB [1] and the Job Monitoring MIB [27].  Enums are
              not used for attributes to which the system administrator may
              assign values.  Values in the range 2**30 to 2**31 - 1 are
              reserved for private or experimental use.  Implementers are
              warned that use of such values may conflict with other
              implementations.  Implementers are encouraged to request
              registration of enum values following the procedures in Section
              6.
         
           uri:  a sequence of characters as defined in rfc1738 and rfc1808.
              This syntax type is used for carrying Universal Resource
              Identifiers.
         
           uriScheme:  a sequence of characters representing the URI Scheme.
              These include 'http' for HTTP schemed URIs (e.g., http://...),
              and 'ftp' for FTP schemed URIs (e.g., ftp://...).
         
           locale:  a standard identifier for human language and optionally a
              country.  The values for this syntax type are taken from RFC 1766
              [26].  RFC 1766 does not have provision for expressing the coded
              character set component of a locale.  The coded character set
              used in the IPP protocol SHALL be UTF-8 [28].
         
              ISSUE: The term 'locale' usually includes country, language, and
              coded character set.  But our data type and RFC 1766 do not
         
         
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              include coded character set.  Should we change the name from
              'locale' to 'human-language' and the corresponding attributes
              from "user-locale" to "user-language", and "printer-locale" to
              "printer-language" (though printer language is what IANA
              registers for our document formats)?
         
           octetString:  a sequence of octets.  This syntax type is used for
              opaque data, such as the document-content.
         
           boolean:  two values of 'true' and 'false'.  This syntax type is
              like a keywordSet, but there are only two values. Note: An
              application might use a checkbox for an attribute with this
              syntax type.
         
           integer:  an integer value that is in the range from -2**31 to
              2**31 - 1.  Each attribute specifies the range constraint
              explicitly if the range is different from the full range of
              possible integer values (e.g., 0 - 100 for the "job-priority"
              attribute).
         
           dateTime:  a standard, fixed length representation of date and time
              (to the nearest second) as defined in RFC 1123 [27].  For
              example, Sun, 06 Nov 1994 08:49:37 GMT.  This is a fixed-length
              subset of that defined by RFC 1123  (an update to RFC 822).  All
              values MUST be represented in Greenwich Mean Time (GMT). This is
              indicated by the inclusion of "GMT" as the three-letter
              abbreviation for time.
         
           seconds:  a non-negative integer with implicit units of seconds.
              This is used for relative time.
         
           milliseconds:  a non-negative integer with implicit units of
              milliseconds.  This is used for relative time.
         
           1setOf  X:  1 or more values of type X.  This syntax type is used
              for multi-valued attributes, whose value is a set of values.
              Note:  The syntax type is called "1setOf" to indicate that set of
              values SHALL NOT be empty (a set of size 0).
         
           rangeOf  X:  a range of value of type X.  This syntax type is used
              for ordered values (numeric, lexical, etc.) such as integers.
         
         
         4.1.1 Attribute Extensibility
         
           This document uses prefixes to the "keyword" and "enum" basic
           syntax type in order to communicate extra information to the reader
           through its name. This extra information need not be represented in
         
         
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           an implementation because it is unimportant to a client or Printer.
           The table below describes the prefixes and their meaning.
         
           "type1":  The IPP standard must be revised to add a new keyword or
              a new enum.  No private keywords or enums are allowed.
         
           "type2":  Implementers can, at any time, add new keyword or enum
              values by proposing them to the IPP working group for
              registration (or an IANA-appointed registry advisor after the IPP
              working group is no longer certified) where they are reviewed for
              approval.  IANA keeps the registry.
         
           "type3":  Implementers can, at any time, add new keyword and enum
              values by submitting a registration request directly to IANA, no
              IPP working group or IANA-appointed registry advisor review is
              required.
         
           "type4":  Anyone (system administrators, system integrators, site
              managers, etc.) can, at any time, add new installation-defined
              values (keywords or new enum values) to a local system. Care
              SHOULD be taken by the implementers to see that keywords do not
              conflict with other keywords defined by the standard or as
              defined by the implementing product. There is no registration or
              approval procedure for type 4 keywords.
         
         Each of the four types above assert some sort of registry or review
         process in order to be valid extensions.  "type1" extensions are only
         valid if the specification is updated, "type2" extensions are only
         valid if the IPP working group or an IANA approved review process
         approves them, "type3" extensions are only valid if IANA registers the
         value with no review process required, and "type4" extensions are
         always valid (there is no review or registration process required).
         Any typeN value MAY be registered using a process for some typeM where
         M is less than N, however such registration is NOT REQUIRED.  For
         example, a type4 value MAY be registered in a type 1 manner (by being
         included in a future version of an IPP specification) however it is
         NOT REQUIRED.
         
         This specification defines keyword and enum values for all of the
         above types, including type4 keywords.
         
         For private (unregistered) keyword extensions, implementers SHOULD use
         keywords with a suitable distinguishing prefix, such as "xxx-" where
         xxx is the (lowercase) company name registered with IANA for use in
         domain names [30].
         
         Note: RFC 1035 [30] indicates that while upper and lower case letters
         are allowed in domain names, no significance is attached to the case.
         
         
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         That is, two names with the same spelling but different case are to be
         treated as if identical.  Also, he labels in a domain name must follow
         the rules for ARPANET host names:  They must start with a letter, end
         with a letter or digit, and have as interior characters only letters,
         digits, and hyphen.  Labels must be 63 characters or less.
         
         ISSUE: Since "." is allowed in fully qualified domain names we must
         state that "." gets mapped to "_" for keywords or we must allow for
         "." in keywords.  Also, why do we not allow uppercase in keywords?
         Should we make keyword be much more broad (all printable ASCII) now
         that we have binary delimeters?
         
         For private (unregistered) enum extension, implementers SHOULD values
         in the reserved integer range (see "enum").
         
         
         
         
         4.2 Job Template Attributes
         
         Job Template attributes describe job processing behavior.  Take for
         example, a generic Job Template attribute called "xxx":
         
           1. "xxx" is optionally supplied by the client in a create request.
              If "xxx" is supplied, the client is specifying that the Printer
              SHALL apply a specific job processing behavior to this job while
              processing the Job.  When "xxx" is not supplied by the client,
              the the Printer applies thedefault job processing behavior.
         
           2. "xxx-supported" is a Printer attribute that describes which
              behaviors are supported by a Printer.  "xxx-supported" is a
              CONDITIONALLY MANDATORY attribute, that is the "xxx-supported"
              attribute is MANDATORY if the Printer is capable of realizing one
              or more of the behaviors associated with the attribute and its
              values.  A client can query the Printer and find out what
              behaviors are supported by inspecting the values of the "xxx-
              supported" attribute.
         
           3. The Printer also supports a default value attribute named "xxx".
              This default value attribute describes what will be done when no
              other job processing information is supplied by the client
              (either explicitly as an IPP attribute in the create request or
              implicitly as an embedded instruction within the job data).
              Along with the supported attribute, the default value attribute
              is also CONDITIONALLY MANDATORY.  However, if the Printer
              supports either the "xxx" default value attribute or the "xxx-
              supported" attribute, the Printer MUST support the other and vice
              versa.
         
         
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           4. If a client application wishes to present an end user with a
              list of supported and default values from which to choose, the
              client program SHOULD query the Printer for the supported and
              default value attributes. The values that the client then
              supplies in the create request will all fall within the supported
              values of the Printer.  When querying the Printer, the client MAY
              enumerate each attribute by name in the Get-Attributes Request,
              or the client MAY just name the "printer-job-template" group in
              order to get the complete set of supported and default value
              attributes which are supported.
         
         The "job-priority" attribute is an example of a Job Template
         attribute.  It is an integer in the range from 1 to 100.  A client can
         query the Printer for the "job-priority-supported" attribute and the
         "job-priority" default value attribute.  The supported attribute
         contains a range of supported priority values.  The default value
         attribute contains the job priority value that will be used for a new
         job if the client does not supply one in the create request.  If the
         client does supply the "job-priority" attribute, the Printer validates
         the value to make sure that it falls within the range of supported
         values.  If the client-supplied value is supported, the Job object is
         created and the "job-priority" attribute is populated with that value.
         The Job object, when queried, returns the value supplied by the
         client.  If the client does not supply a "job-priority" value in the
         create request, the Job object is created, but no "job-priority"
         attribute is associated with the Job.  The client queries the
         Printer's default value "job-priority" value to find out at what
         priority the job will be processed.
         
         The table below summarizes the names, relationships, and conformance
         requirements for all Job Template attributes.  The following general
         rules apply to implementation requirements:
         
           1. In a create request, all Job Template attributes are OPTIONAL.
         
           2. In a Printer Object, all supported attributes ("xxx-supported")
              are CONDITIONALLY MANDATORY.
         
           3. All Printer default value attributes ("xxx") are CONDITIONALLY
              MANDATORY.
         
           Note:  If the Printer implements either the default value attribute
              or the supported values attribute, the Printer MUST also
              implement the other and vice versa.
         
         The table only shows exceptions to the above rules.   The first column
         of the table (Job) shows the name and syntax for each Job Template
         
         
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         attribute in the Job object (in the create request, the same name and
         syntax is used). All of the attributes in the first column make up the
         "job-template" group.  The last two columns show the name and syntax
         for each Job Template attribute in the Printer object (the default
         value attribute and the supported attribute).  A "No" in the table
         means the Printer SHALL NOT support the attribute.  A "MAN" indicates
         that the attribute is MANDATORY.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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           +-------------------+----------------------+----------------------+
           |    Job            |Printer: Default Value|  Printer: Supported  |
           +===================+======================+======================+
           | job-name          | No                   | No                   |
           | (name, MAN)       |                      |                      |
           +-------------------+----------------------+----------------------+
           | job-sheets        | job-sheets           |job-sheets-supported  |
           | (type4 keyword)   | (type4 keyword)      |(1setOf type4 keyword)|
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | notify-events     | notify-events        | notify-events-       |
           |(1setOf            |(1setOf type2 keyword)| supported            |
           | type2 keyword)    |                      |(1setOf type2 keyword)|
           +-------------------+----------------------+----------------------+
           |notify-addresses   | No                   |notify-addresses      |
           |(1setOf uri)       |                      |-supported            |
           |                   |                      |(1setOf uri scheme)   |
           +-------------------+----------------------+----------------------+
           | job-priority      | job-priority         |job-priority-supported|
           | (integer 1-100)   | (integer 1-100)      |(rangeOf integer      |
           |                   |                      | 1-100)               |
           +-------------------+----------------------+----------------------+
           | job-hold-until    | job-hold-until       | job-hold-until-      |
           | (type4 keyword)   | (type4 keyword)      | supported            |
           |                   |                      |(1setOf type4 keyword)|
           +-------------------+----------------------+----------------------+
           |multiple-document- |multiple-document-    |multiple-document-    |
           | handling          | handling             |handling-supported    |
           | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
           +-------------------+----------------------+----------------------+
           | best-effort       | best-effort          | best-effort-supported|
           | (boolean)         | (boolean, MAN)       |(boolean, MAN)        |
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | media             | media                | media-supported      |
           | (type4 keyword)   | (type4 keyword)      |(1setOf type4 keyword)|
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | number-up         | number-up            | number-up-supported  |
           | (type3 keyword)   | (type3 keyword)      |(1setOf type3 keyword)|
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | sides             | sides                | sides-supported      |
           | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | printer-resolution| printer-resolution   | printer-resolution-  |
         
         
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           | (type2 enum)      | (type2 enum)         | supported            |
           |                   |                      |(1setOf type2 enum)   |
           +-------------------+----------------------+----------------------+
           | print-quality     | print-quality        | print-quality-       |
           | (type2 enum)      | (type2 enum)         | supported            |
           |                   |                      |(1setOf type2 enum)   |
           +-------------------+----------------------+----------------------+
           | finishings        | finishings           | finishings-supported |
           |(1setOf type2 enum)|(1setOf type2 enum)   |(1setOf type2 enum)   |
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | copies            | copies               | copies-supported     |
           | (integer: 1 - MAX)| (integer: 1 - MAX)   | (rangeOf integer     |
           |                   |                      |     1- MAX)          |
           +-------------------+----------------------+----------------------+
           | document-format   | document-format      | document-format-     |
           | (type2 enum)      | (type2 enum)         | supported            |
           |                   |                      |(1setOf type2 enum)   |
           +-------------------+----------------------+----------------------+
           | compression       | No                   | compression-supported|
           | (type3 keyword)   |                      |(1setOf type3 keyword)|
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | job-k-octets      | No                   |job-k-octets-supported|
           | (integer)         |                      | (rangeOf integer)    |
           |                   |                      |                      |
           +-------------------+----------------------+----------------------+
           | job-impressions   | No                   | job-impressions-     |
           | (integer)         |                      | supported            |
           |                   |                      | (rangeOf integer)    |
           +-------------------+----------------------+----------------------+
           | job-media-sheets  | No                   | job-media-sheets-    |
           | (integer)         |                      | supported            |
           |                   |                      | (rangeOf integer)    |
           +-------------------+----------------------+----------------------+
         
         4.2.1 job-name (name)
         
         This attribute is the name of the job.  It is a name that is more user
         friendly than the "job-uri" attribute value.  It does not need to be
         unique.
         
         If "job-name" is not supplied in the create request, the Printer, on
         creation of the Job, SHALL generate a name.  The name MAY be generated
         using the name of the first Document in the Job (the "document-name"
         attribute).  If "job-name" is supplied in the create request, the
         Printer SHALL use its value as the name of the created Job.
         
         
         
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         4.2.2 job-sheets (type4 keyword)
         
         This attribute determines which if any banner page(s) SHALL be printed
         with a job.
         
         Standard values are:
         
           'none': no job sheet is printed
           'standard': a site specific standard job sheet (start only) or
              sheets (start and end) is printed
         
         To force no job sheets, the system administrator SHALL set the
         supported value to only 'none'.  To force the use of banner pages, the
         supported values SHALL not include 'none'.  In this case, if a client
         requests 'none', the create request is rejected.
         
         4.2.3 notify-events (1setOf type2 keyword)
         
         This attribute specifies the events for which the end user desires
         some sort of notification.  The "notify-addresses" attribute is used
         to describe the destination addresses for these events.
         
         Standard values are:
         
           'none': the Printer SHALL not notify.
           'all': the Printer SHALL notify when any of the events occur.
           'job-completion':  the Printer SHALL notify when the job containing
              this value completes (i.e., enters the 'completed', 'canceled',
              or 'aborted' state) with or without errors.
           'job-problems':  the Printer SHALL notify when this job has a
              problem while this job is processing (i.e., when the Job moves
              from the 'processing' to the 'processing-stopped' state).
              Problems include any of the "job-state-reasons" or "printer-
              state-reason" values.
           'printer-problems': the Printer SHALL notify when this job is
              affected by a Printer problem.  This happens when the printer
              enters the 'stopped' state while this job is in the 'pending',
              'pending-held', 'processing', or 'processing-stopped' state.  If
              the Printer enters the 'stopped' state the reason in the
              "printer-state-reasons" attribute.
         
         
         4.2.4 notify-addresses (1setOf uri)
         
         This attribute describes both where (the address) and how (the
         mechanism for delivery ) events are to be delivered. The Printer SHALL
         use this attribute as the set of addresses and methods for sending
         
         
         
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         messages when an event occurs that the end user (job submitter) has
         registered an interest in.
         
         Standard uri scheme values are:
         
           'mailto': email is used
           'http': an HTTP  method is used to add HTML formatted events to the
              end of the specified HTML file.
           'ftp': FTP is used to append a record at the end of a specified
           text file.
         
         4.2.5 job-priority (integer(1:100))
         
         This attribute specifies a priority for scheduling the print-job. A
         higher value specifies a higher priority. The value 1 is defined to
         indicate the lowest possible priority. The value 100 is defined to
         indicate the highest possible priority.  Among those jobs that are
         ready to print, a Printer SHALL print all jobs with a priority value
         of n before printing those with a priority value of n-1 for all n.
         The mapping of vendor-defined priority over this range is
         implementation-specific.
         
         4.2.6 job-hold-until (type4 keyword)
         
         This job attribute specifies the named time period during which the
         Job print job SHALL become a candidate for printing.
         
         Standard values for named time periods are:
         
           'no-hold': immediately, if there are not other reasons to hold the
              job.
           'day-time': during the day.
           'evening': evening
           'night': night
           'weekend': weekend
           'second-shift': second-shift
           'third-shift': third-shift (after midnight)
         
         
         An administrator SHALL associate allowable print times with a named
         time period (by means outside IPP 1.0).  An administrator is
         encouraged to pick names that suggest the type of time period.
         
         If the value of this attribute specifies a time period that is in the
         future, the Printer SHALL add the 'job-hold-until-specified' value to
         the job's "job-state-reasons" attribute, move the job to the 'pending-
         held' state, and SHALL NOT schedule the job for printing until the
         specified time-period arrives.  When the specified time period
         
         
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         arrives, the Printer SHALL remove the 'job-hold-until-specified' value
         from the job's "job-state-reason attribute" and, if no other job
         reasons remain, SHALL consider the job as a candidate for processing
         by moving the job to the 'pending' state.
         
         If this job attribute value is the named value 'no-hold', or the time
         period has already started , the job SHALL be a candidate for
         processing immediately.
         
         4.2.7 multiple-documenthandling (type2 keyword)
         
         This job attribute is relevant only if a job consists of two or more
         documents. It controls finishing operations, job-sheet placement, and
         the order of documents when the copies attribute exceeds 1.
         
         Standard values are:
         
           'single-document': If the files for the job are a and b, then files
              a and b SHALL be treated as a single document for finishing
              operations. Also, there SHALL be no slip sheets between files a
              and b and the Printer SHALL NOT force each document to start on a
              new page or new media sheet.  If more than one copy is made, the
              ordering SHALL be a, b, a, b, ...., and the Printer SHALL force
              each copy to start on a new sheet.
           'separate-documents-uncollated-copies': If the files for the job
              are a and b, then each file SHALL be treated as a single document
              for finishing operations. Also, a client may specify that a slip
              sheet be placed between files a and b and the Printer shall force
              each document copy to start on a new sheet.  If more than one
              copy is made, the ordering SHALL be a, a, b, b, ....
           'separate-documents-collated-copies': If the files for the job are
              a and b, then each file SHALL be treated as a single document for
              finishing operations. Also, a client may specify that a slip
              sheet be placed between files a and b. If more than one copy is
              made, the ordering SHALL be a, b, a, b, ...., and the Printer
              shall force each document copy to start on a new sheet
         
         
         
         
         4.2.8 best-effort (boolean)
         
         This attribute determines how to control a conflict between what a
         client requests in a create request and what a Printer supports.  The
         value 'true' means that a best effort attempt to print the Job is
         possible (or acceptable).  In order to achieve this, the Printer might
         have to substitute some supported value for a requested value which is
         unsupported.  The value 'false' means that total fidelity is required;
         
         
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         a best effort attempt to print the Job is not possible (or not
         acceptable).  In other words, the job must be printed exactly as
         specified in the create request.  If one or more of the client-
         supplied values in the create request is not supported by the Printer,
         the Printer rejects the create request.
         
         There are two cases to consider:
         
           - The Printer's "best-effort-supported" attribute is set to 'true':
              This indicates that the Printer is capable of best effort
              printing.  In this case either the "best-effort" Job Template
              attribute in the create request or the Printer's "best-effort"
              (the default value attribute) can be set to either 'true' or
              'false'.  If "best-effort" is set to 'false' the Printer ensures
              full fidelity of the other IPP attributes in the create request.
              That is, if any other attribute in the create-request is set to a
              value that is not supported, the Printer rejects the create
              request.  If "best-effort" attribute is set to 'true', the the
              Printer makes whatever substitutions are necessary to ensure that
              the job is printed.  For example, if a client supplies a
              "finishings" Job Template attribute set to 'staple' but the
              printer does not support stapling (not a feature or it is
              temporarily out of staples) then if the "best-effort" attribute
              is set to 'true' the job can still be printed but it is not
              stapled.  If "best-effort" is set to 'false', the create request
              is rejected since the Printer can not guarantee that the job will
              be stapled.
         
           - The Printer's "best-effort-supported" attribute is set to
              'false':  This indicates that the Printer is not capable of (or
              will not support) best effort printing.  The Job Template
              attributes supplied by the client in the create request must
              match all of the Printer's supported values, or else the Printer
              rejects the create request.  In this case Printer's "best-effort"
              attribute (the default value attribute) MUST also be set to
              'false'.  If the client supplies the "best-effort" Job Template
              create request, it too MUST be set to 'false'.  If it is set to
              'true', the Printer rejects the create request.
         
         Note: that the "best-effort" attribute in a create request is unlikely
         to be used much. Many clients will submit a job with no attributes,
         and the Printer will use default values.  Other clients will submit a
         job via a GUI that limits the attribute values to values which are
         supported.  Best-effort is useful in the GUI context only if a user
         expects the job to be moved to another printer and prefers a sub-
         optimal result to nothing at all.  Best-effort is most useful in the
         case where an end-user uses a command line interface to request
         attributes that might not be supported.
         
         
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         4.2.9 media (type4 keyword)
         
         This job attribute identifies the medium that the Printer uses for all
         pages of the Job.
         
         The values for "media" include medium-names, medium-sizes, input-trays
         and electronic forms so that one attribute specifies the media. If a
         printer allows a client to specify a medium name as the value of this
         attribute, such a medium name implicitly selects an input-tray that
         contains the specified medium.  If a printer allows a client to
         specify a medium size as the value of this attribute, such a medium
         size implicitly selects a medium name which in turn implicitly selects
         an input-tray that contains the medium with the specified size.  If a
         printer allows a client to specify an input-tray as the value of this
         attribute, such an input-tray implicitly selects the medium that is in
         that input-tray at the time the job prints. This case includes manual-
         feed input-trays.  If a printer allows a client to specify an
         electronic form as the value of this attribute, such an electronic
         form implicitly selects a medium-name which in turn implicitly selects
         an input-tray that contains the medium specified by the electronic
         form. The electronic form also implicitly selects an image that the
         Printer SHALL merge with the data from the document as its prints each
         page.
         
         Standard values are (taken from ISO DPA and the Printer MIB) and are
         listed in section 13.
         4.2.10 number-up (type3 keyword)
         
         This job attribute specifies the number of source page-images to
         impose upon a single side of an instance of a selected medium.
         
         Standard values are:
         
           'none': The Printer SHALL not include any embellishments and SHALL
              place one logical page on a single side of an instance of the
              selected medium without any translation, scaling, or rotation.
           'one': The Printer SHALL place one logical page on a single side of
              an instance of the selected medium (MAY add some sort of
              translation, scaling, or rotation).
           'two': The Printer SHALL place two logical page on a single side of
              an instance of the selected medium (MAY add some sort of
              translation, scaling, or rotation).
           'four': The Printer SHALL place four logical page on a single side
              of an instance of the selected medium (MAY add some sort of
              translation, scaling, or rotation).
         
         
         
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         This attribute primarily controls the translation, scaling and
         rotation of page images, but a site may choose to add embellishments,
         such as borders to each logical page.
         
         4.2.11 sides (type2 keyword)
         
         This attribute specifies how source page-images are to be imposed upon
         the sides of an instance of a selected medium.
         
         The standard values are:
         
           'one-sided': imposes each consecutive source page-image upon the
              same side of consecutive media sheets.
           'two-sided-long-edge': imposes each consecutive pair of source
              page-image upon front and back sides of consecutive media sheets,
              such that the orientation of each pair of source-pages on the
              medium would be correct for the reader as if for binding on the
              long edge.  This imposition is sometimes called 'duplex'.
           'two-sided-short-edge': imposes each consecutive pair of source
              page-image upon front and back sides of consecutive media sheets,
              such that the orientation of each pair of source-pages on the
              medium would be correct for the reader as if for binding on the
              short edge.  This imposition is sometimes called 'tumble' or
              'head-to-toe'.
         
         'two-sided-long-edge', 'two-sided-short-edge', 'tumble'. 'duplex', and
         'head-to-toe' all work the same for portrait or landscape, that is,
         'head-to-toe' is 'tumble' in portrait but 'duplex' in landscape.
         'head-to-head' also switches between 'duplex' and 'tumble' when using
         portrait and landscape modes.
         
         4.2.12 printer-resolution (type2 enum)
         
         This attribute identifies the resolution that Printer uses for a
         certain Job.
         
         The values are type2 enums which represent single integers or pair of
         integers. The latter are to specify the resolution when the x and y
         dimensions differ. When two integers are specified, the first is in
         the x direction, i.e., in the direction of the shortest dimension of
         the medium, so that the value is independent of whether the printer
         feeds long edge or short edge first.
         
         The standard values are:
         
         
         
           'normal'(3):
         
         
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           'res-100'(4):  100 x 100 dpi
           'res-200'(5):  200 x 200 dpi
           'res-240'(6):  240 x 240 dpi
           'res-300'(7):  300 x 300 dpi
           'res-360'(8):  360 x 360 dpi
           'res-400'(9):  400 x 400 dpi
           'res-600'(10):  600 x 600 dpi
           'res-720'(11):  720 x 720 dpi
           'res-800'(12):  800 x 800 dpi
           'res-1200'(13):  1200 x 1200 dpi
           'res-1440'(14):  1440 x 1440 dpi
           'res-1600'(15):  1600 x 1600 dpi
           'res-1800'(16):  1800 x 1800 dpi
           'res-100x200'(100):  100 x 200 dpi
           'res-200x100'(101):  200 x 100 dpi
           'res-300x600'(102):  300 x 600 dpi
           'res-600x300'(103):  600 x 300 dpi
           'res-360x720'(104):  360 x 260 dpi
           'res-720x360'(105):  720 x 360 dpi
           'res-400x800'(106):  400 x 800 dpi
           'res-800x400'(107):  800 x 400 dpi
           'res-600x1200'(108):  600 x 1200 dpi
           'res-1200x600'(109):  1200 x 600 dpi
           'res-720x1440'(110):  720 x 1440 dpi
           'res-1440x720'(111):  1440 x 720 dpi
           'res-1800x600'(112):  1800 x 600 dpi
         
         ISSUE: Should we add metric enums?  Such as
         
           'res-8x3.85'(200):  8 lines per 3.85 mm (fax)
           'res-8x7.7'(201): 8 lines per 7.7 mm (fax)
           'res-8x15.4'(202): 8 lines per 15.4 mm (fax)
           'res-16x15.4'(203): 16 lines per 15.4 mm (fax)
         
         
         
         4.2.13 print-quality (type2 enum)
         
         This attribute specifies the print quality that the Printeruses for a
         certain Job.
         
         The standard values are:
         
           'draft'(3): lowest quality available on the printer
           'normal'(4): normal or intermediate quality on the printer
           'high'(5): highest quality available on the printer
         
         
         
         
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         4.2.14 copies (integer(1:2**31 - 1))
         
         This attribute specifies the number of copies of the job to be
         printed.
         
         Note: The effect of this attribute on job with multiple documents is
         controlled by the "multiple-document-handling" job attribute (section
         4.2.7).
         
         
         
         4.2.15 finishing (1setOf type2 enum)
         
         This attribute identifies the finishing operations that the Printer
         uses for each copy of each printed document in a particular Job. The
         definition of a copy for Jobs with multiple documents is controlled by
         the "multiple-document-handling" attribute.
         
         Standard values are:
         
           'none'(3):  Perform no finishing
           'staple'(4):  Bind the document(s) with one or more staples. The
              exact number and placement of the staples is site-defined.
           'staple-top-left'(5):  Place one or more staples on the top left
              corner of the document(s).
           'staple-bottom-left'(6):  Place one or more staples on the bottom
              left corner of the document(s).
           'staple-top-right'(7):  Place one or more staples on the top right
              corner of the document(s).
           'staple-bottom-right'(8):  Place one or more staples on the bottom
              right corner of the document(s).
           'saddle-stitch'(9):  Bind the document(s) with one or more staples
              (wire stitches) along the middle fold.  The exact number and
              placement of the stitches is site-defined.
           'edge-stitch'(10):  Bind the document(s) with one or more staples
              (wire stitches) along one edge.  The exact number and placement
              of the staples is site-defined.
           'punch'(11):  This value indicates that holes are required in the
              finished document. The exact number and placement of the holes is
              site-defined  The punch specification MAY be satisfied (in a
              site- and implementation-specific manner) either by
              drilling/punching, or by substituting pre-drilled media.
           'cover'(12):  This value is specified when it is desired to select
              a non-printed (or pre-printed) cover for the document. This does
              not supplant the specification of a printed cover (on cover stock
              medium) by the document itself.
         
         
         
         
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           'bind'(13):  This value indicates that a binding is to be applied
              to the document; the type and placement of the binding is site-
              defined."
         4.2.16 document-format (type2 keyword)
         
         This attribute defines the document format for each Document in a Job.
         The standard values for this attribute are enums.  Since the complete
         list is rather long, the full enumeration of standard values is found
         in section 12 APPENDIX C: "document-format" enum values.
         
         If the "document-format" is unknown for a certain document, the client
         SHALL NOT supply the attribute in the create request or the Send-
         Document Request.
         
         4.2.17 compression (type3 keyword)
         
         This attribute identifies compression algorithms used for compressed
         document data.
         
         Standard values for this attribute are:
         
           'none': no compression is used.
           'zip':ZIP compression technology
           'tar': UNIX TAR compression technology
         
         
         4.2.18 job-k-octets (integer(0:2**31 - 1))
         
         This attribute specifies the total size of the job in K octets, i.e.,
         in units of 1024 octets.  The value SHALL be rounded up, so that a job
         between 1 and 1024 octets SHALL be indicated as being 1, 1025 to 2048
         SHALL be 2, etc.
         
         Note:  This attribute and the following two attributes ("job-
         impressions" and "job-media-sheets") are not intended to be  counters;
         they are intended to be useful routing and scheduling information if
         known. The Printer tries to compute the value if it is not supplied in
         the create request.  The Printer, however, might not be able to
         compute this value at the time the Job is created.  If not, the
         Printer may support this attribute at any later time as it is able to
         compute value.
         
         4.2.19 job-impressions (integer(0:2**31 - 1))
         
         This attribute specifies the total size of the job in impressions.
         
         
         
         
         
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         4.2.20 job-media-sheets (integer(0:2**31 - 1))
         
         This attribute specifies the total size of the job in media-sheets.
         
         
         4.3 Job Description Attributes
         
         The attributes in this section form the attribute group called "job-
         description".  The following table summarizes these attributes.  The
         third column indicates whether the attribute is a MANDATORY attribute.
         If it is not MANDATORY, then it is OPTIONAL.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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         +----------------------------+----------------------+----------------+
         |      Attribute             |     Syntax           |   MANDATORY?   |
         +----------------------------+----------------------+----------------+
         | job-uri                    | uri                  |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | job-uri-user               | uri                  |                |
         +----------------------------+----------------------+----------------+
         | job-originating-user       | name                 |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | job-originating-host       | name                 |                |
         +----------------------------+----------------------+----------------+
         | user-locale                | locale               |                |
         +----------------------------+----------------------+----------------+
         | job-state                  | type1 enum           |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | job-state-reasons          | 1setOf type2 keyword |                |
         +----------------------------+----------------------+----------------+
         | job-state-message          | text                 |                |
         +----------------------------+----------------------+----------------+
         | output-device-assigned     | name                 |                |
         +----------------------------+----------------------+----------------+
         | time-since-pending         | milliseconds         |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | time-since-processing      | milliseconds         |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | time-since-completed       | milliseconds         |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | number-of-intervening-jobs | integer              |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | job-message-from-operator  | text                 |                |
         +----------------------------+----------------------+----------------+
         | job-k-octets-processed     | integer              |                |
         +----------------------------+----------------------+----------------+
         | job-impressions-completed  | integer              |                |
         +----------------------------+----------------------+----------------+
         | job-media-sheets-completed | integer              |                |
         +----------------------------+----------------------+----------------+
         
         4.3.1 job-uri (uri)
         
         This attribute contains the URI for the job.  The Printer, on receipt
         of a new job, generates a URI which identifies the new Job on that
         Printer. The Printer returns the value of the "job-uri" attribute as
         part of the response to a create request.   The precise format of a
         job URI is implementation dependent.
         
         
         
         
         
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         4.3.2 job-uri-user (uri)
         
         Similar to "job-uri", this attribute contains the URI referencing an
         HTML page containing information about the Job.
         
         4.3.3 job-originating-user (name)
         
         This attribute specifies the user name of the person submitting the
         print job.  The Printer SHALL set this attribute to the most
         authenticated name that it can obtain from the protocol over which the
         operation was received from the client.
         
         4.3.4 job-originating-host (name)
         
         This attribute identifies the originating host of the job. The Printer
         SHALL set this attribute to the most authenticated host name it can
         obtain from the protocol over which the operation was received from
         the client.
         
         4.3.5 user-locale (locale)
         
         This attribute identifies the human language and optional the country
         of the end user.  The Printer sets this attribute to the most reliable
         value it can obtain from the protocol over which the Print operation
         was received from the client.
         
         The Printer uses this attribute to determine the locale it SHOULD use
         for localizing any text strings that it sends back to the end user.
         These include status messages, text attributes, and notification
         messages.
         
         4.3.6 job-state (type1 enum)
         
         This attribute identifies the current state of the job.  Even though
         the IPP protocol defines eight values for job states, implementations
         only need to support those states which are appropriate for the
         particular implementation.  In other words, a Printer supports only
         those job states implemented by the output device and available to the
         Printer object implementation.
         
         Standard values are:
         
           'unknown'(2):  The job state is not known, or its state is
              indeterminate.
           'pending'(3):  The job is a candidate to start processing, but is
              not yet processing.
           'pending-held'(4):  The job is not a candidate for processing for
              any number of reasons but will return to the 'pending' state as
         
         
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              soon as the reasons are no longer present.  The job's "job-state-
              reason" attribute SHALL indicate why the job is no longer a
              candidate for processing.
           'processing'(5):  Either:
              1.  the job is using, or is attempting to use, one or more
                document transforms which include (1) purely software
                processes that are interpreting a PDL, and (2) hardware
                devices that are interpreting a PDL, making marks on a medium,
                and/or performing finishing, such as stapling OR
              2.  the server has made the job ready for printing, but the
                output device is not yet printing it, either because the job
                hasn't reached the output device or because the job is queued
                in the output device or some other spooler, awaiting the
                output device to print it.
              When the job is in the 'processing' state, the entire job state
              includes the detailed status represented in the printer's
              "printer-state", "printer-state-reasons", and "printer-state-
              message" attributes.
              Implementations MAY include additional values in the job's "job-
              state-reasons" attribute to indicate the progress of the job,
              such as adding the 'job-printing' value to indicate when the
              output device is actually making marks on paper.  Most
              implementations won't bother with this nuance.
           'processing-stopped'(6):  The job has stopped while processing for
              any number of reasons and will return to the 'processing' state
              as soon as the reasons are no longer present.
              The job's "job-state-reason" attribute MAY indicate why the job
              has stopped processing.  For example, if the output device is
              stopped, the 'printer-stopped' value MAY be included in the job's
              "job-state-reasons" attribute.  For example, if the output device
              is stopped, the 'printer-stopped' value MAY be included in the
              job's "job-state-reasons" attribute.
              NOTE - When an output device is stopped, the device usually
              indicates its condition in human readable form locally at the
              device.  A client can obtain more complete device status remotely
              by querying the printer's "printer-state", "printer-state-
              reasons" and "printer-state-message" attributes.
           'canceled'(7):  The job has been canceled by a Cancel-Job operation
              and is either (1) in the process of terminating or (2) has
              completed terminating.  The job's "job-state-reasons" attribute
              SHOULD contain either the 'canceled-by-user' or 'canceled-by-
              operator' value.
           'aborted'(8):  The job has been aborted by the system, usually
              while the job was in the 'processing' or 'processing-stopped'
              state.
           'completed'(9):  The job has completed successfully or with
              warnings or errors after processing and all of the job media
              sheets have been successfully stacked in the appropriate output
         
         
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              bin(s).  The job's "job-state-reasons" attribute SHOULD contain
              one of: 'completed-successfully', 'completed-with-warnings', or
              'completed-with-errors' values.
         
         The final value for this attribute SHALL be one of: 'completed',
         'canceled', or 'aborted' before the Printer removes the job
         altogether.  The length of time that jobs remain in the 'canceled',
         'aborted', and 'completed' states depends on implementation.
         
         The following figure shows the normal job state transitions.
         
                                                             +----> canceled
                                                            /
             +----> pending --------> processing ---------+------> completed
             |         ^                   ^                \
         --->+         |                   |                 +----> aborted
             |         v                   v                /
             +----> pending-held    processing-stopped ----+
         
         
         Normally a job progresses from left to right.  Other state transitions
         are unlikely, but are not forbidden.  Not shown are the transitions to
         the 'canceled' state from the 'pending', 'pending-held', 'processing',
         and 'processing-stopped' states.
         
         4.3.7 job-state-reasons (1setOf  type2 keyword)
         
         This attribute provides additional information about the job's current
         state, i.e., information that augments the value of the job's "job-
         state" attribute.
         
         Implementation of these values is OPTIONAL, i.e., a Printer NEED NOT
         implement them, even if (1) the output device supports the
         functionality represented by the reason and (2) is available to the
         Printer object implementation.  These values MAY be used with any job
         state or states for which the reason makes sense.  Furthermore, when
         implemented, the Printer SHALL return these values when the reason
         applies and SHALL NOT return them when the reason no longer applies
         whether the value of the job's "job-state" attribute changed or not.
         When the job does not have any reasons for being in its current state,
         the Printer shall set the value of the job's "job-state-reasons"
         attribute to 'none'.
         
         NOTE - While values cannot be added to the 'job-state' attribute
         without impacting deployed clients that take actions upon receiving
         "job-state"values, it is the intent that additional "job-state-
         reasons" values can be defined and registered without impacting such
         
         
         
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         deployed clients.  In other words, the "job-state-reasons" attribute
         is intended to be extensible.
         
         The following standard values are defined:
         
         NOTE - For easy of understanding the order of the reasons is presented
         in the order in which the reason is most likely to occur:
         
           'none':  There are no reasons for the job's current state.
           'job-incoming':  The CreateJob operation has been accepted by the
              Printer, but the Printer is expecting additional SendDocument
              operations and/or is accessing/accepting document data.
           'job-outgoing':  The Printer is transmitting the job to the output
              device.
           'job-hold-until-specified':  The value of the job's "job-hold-
              until" attribute specifies a time period that is still in the
              future.  The job SHALL NOT be a candidate for processing until
              this reason is removed and there are no other reasons to hold the
              job.
           'resources-are-not-ready':  At least one of the resources needed by
              the job, such as media, fonts, resource objects, etc., is not
              ready on any of the physical printer's for which the job is a
              candidate.  This condition MAY be detected when the job is
              accepted, or subsequently while the job is pending or processing,
              depending on implementation.
           'printer-stopped-partly':  The value of the Printer's "printer-
              state-reasons" attribute contains the value 'stopped-partly'.
           'printer-stopped':  The value of the Printer's "printer-state"
              attribute is 'stopped'.
           'job-printing':  The output device is marking media. This value is
              useful for Printers which spend a great deal of time processing
              when no marking is happening and then want to show that marking
              is now happening.
           'job-cancelled-by-user':  The job was cancelled by the user using
              the CancelJob request, i.e., by a user whose name is the same as
              the value of the job's "job-originating-user" attribute.
           'job-cancelled-by-operator':  The job was cancelled by the operator
              using the CancelJob request, i.e., by a user whose name is
              different than the value of the job's "job-originating-user"
              attribute.
           'job-completed-successfully':  The job completed successfully.
           'job-completed-with-warnings':  The job completed with warnings.
           'job-completed-with-errors':  The job completed with errors (and
              possibly warnings too).
           'logfile-pending ':  The job's logfile is pending file transfer.
           'logfile-transferring':  The job's logfile is being transferred.
         
         
         
         
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         4.3.8 job-state-message (text)
         
         This attributes specifies supplemental information about the Job State
         in human readable text.
         
         4.3.9 output-device-assigned (name)
         
         This attribute identifies the Output Device to which the Printer has
         assigned this job.  If an output device implements an embedded IPP
         Printer, the Printer NEED NOT set this attribute.  If a Print Server
         implements a Printer, the value MAY be empty until the Printer assigns
         an output device to the job.
         
         4.3.10 time-since-pending (milliseconds)
         
         This attribute indicates the amount of time that has passed since the
         Job was first put into the pending state..
         
         4.3.11 time-since-processing (milliseconds)
         
         This attribute indicates the amount of time that has passed since the
         Job first entered the processing state.
         
         4.3.12 time-since-completed (milliseconds)
         
         This attribute indicates the amount of time that has passed since the
         Job was completed.
         
         4.3.13 number-of-intervening-jobs (integer(0:2**31 - 1))
         
         This attribute indicates the number of jobs that are "ahead" of this
         job in the current scheduled order.  For efficiency, it is only
         necessary to calculate this value when an operation is performed that
         requests this attribute.
         
         Note: This attribute is necessary since an end user may request just
         their own jobs and they need some relative position indicator if there
         are other jobs interspersed in the waiting list which are not returned
         in the response or cannot be because of site security policy
         restrictions.
         
         4.3.14 job-message-from-operator (text)
         
         This attribute provides a message from an operator, system
         administrator or "intelligent" process to indicate to the end user the
         reasons for modification or other management action taken on a job.
         
         
         
         
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         4.3.15 job-k-octets-processed (integer(0:2**31 - 1))
         
         This attribute specifies the number of octets completed in K octets,
         i.e., in units of 1024 octets.  The value SHALL be rounded up, so that
         a job between 1 and 1024 octets SHALL be indicated as being 1, 1025 to
         2048 SHALL be 2, etc.
         
         Note: This attribute and the following two attributes ("job-
         impressions-completed" and "job-sheets-completed") are intended to be
         counters as in the Job Monitoring MIB [27].
         
         4.3.16 job-impressions-completed  (integer(0:2**31 - 1))
         
         This job attribute specifies the number of impressions completed. This
         attribute is intended to be a counter as in the Job Monitoring MIB.
         
         4.3.17 job-media-sheets-completed (integer(0:2**31 - 1))
         
         This job attribute specifies the media-sheets completed. This
         attribute is intended to be a counter as in the Job Monitoring MIB.
         
         
         4.4 Document Attributes
         
         This group of attributes describes the document data for the job.  For
         single-Document Jobs, they are supplied in the Print-Job or Print-URI
         requests.  For multi-Document Jobs, they are supplied in each Send-
         Document or Send-URI request.
         
         +----------------------------+----------------------+----------------+
         |      Attribute             |     Syntax           |   MANDATORY?   |
         +----------------------------+----------------------+----------------+
         | document-name              | name                 |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | document-format            | type 2 enum          |                |
         +----------------------------+----------------------+----------------+
         | document-uri               | uri                  |                |
         +----------------------------+----------------------+----------------+
         
         4.4.1 document-name (name)
         
         This attribute contains the name of the document used by the client to
         initially identify the document. When a client prints by reference,
         i.e. includes the document-URI attribute and no document content, this
         attribute SHALL be absent.
         
         
         
         
         
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         4.4.2 document-format (type2 enum)
         
         See section 4.2.16 that describes the "document-format" Job Template
         attribute.
         
         4.4.3 document-uri (uri)
         
         This attribute contains the URI of the document when the document
         content is not included in the Send Document operation.  Document-
         number is the only other attribute allowed when a document-URI
         attribute is present in a Send Document operation.
         
         
         
         
         4.5 Printer Description Attributes
         
         These attributes form the attribute group called "printer-
         description".  A Printer object may be realized in either a print
         server or output device.  Note: How these attributes are set by an
         Administrator is outside the scope of this specification.  The
         following table summarizes these attributes, their syntax, and whether
         or not they are MANDATORY.  If they are not MANDATORY, they are
         OPTIONAL.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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         +----------------------------+----------------------+----------------+
         |      Attribute             |     Syntax           |   MANDATORY?   |
         +----------------------------+----------------------+----------------+
         | printer-uri                | uri                  |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | printer-uri-user           | uri                  |                |
         +----------------------------+----------------------+----------------+
         | printer-name               | name                 |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | printer-location           | text                 |                |
         +----------------------------+----------------------+----------------+
         | printer-description        | text                 |                |
         +----------------------------+----------------------+----------------+
         | printer-more-info-site     | uri                  |                |
         +----------------------------+----------------------+----------------+
         | printer-driver-installer   | uri                  |                |
         +----------------------------+----------------------+----------------+
         | printer-make-and-model     | text                 |                |
         +----------------------------+----------------------+----------------+
         | printer-more-info-         | uri                  |                |
         | manufacturer               |                      |                |
         +----------------------------+----------------------+----------------+
         | printer-state              | type1 enum           |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | printer-state-reasons      | type2 keyword        |                |
         +----------------------------+----------------------+----------------+
         | printer-state-message      | text                 |                |
         +----------------------------+----------------------+----------------+
         | printer-is-accepting-jobs  | boolean              |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | queued-job-count           | integer              |                |
         +----------------------------+----------------------+----------------+
         | printer-message-from-      | text                 |                |
         | operator                   |                      |                |
         +----------------------------+----------------------+----------------+
         | printer-locale             | locale               |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | printer-locales-supported  | 1setOf locale        |  MANDATORY     |
         +----------------------------+----------------------+----------------+
         | color-supported            | boolean              |                |
         +----------------------------+----------------------+----------------+
         
         4.5.1 printer-uri (uri)
         
         This attribute contains the URI for the printer.  An administrator
         SHALL determine a printer's URI and SHALL set this attribute to that
         URI. The precise format of a printer URI SHALL be implementation
         dependent.
         
         
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         4.5.2 printer-uri-user (uri)
         
         Similar to "printer-uri", this attribute contains the URI for an HTML
         page with more information about this printer.
         
         4.5.3 printer-name (name)
         
         This attribute contains the name of the printer. It is a name that is
         more user friendly than the printer-URI. An administrator SHALL
         determine a printer's name and SHALL set this attribute to that name.
         This name may be the last part of the printer's URI or it may be
         unrelated. In non-US-English locales, a name may contain characters
         that are not allowed in a URI.
         
         4.5.4 printer-location (text)
         
         This attribute identifies the location of this printer.
         
         4.5.5 printer-description (text)
         
         This attribute identifies the descriptive information about the this
         Printer.  This could include things like: "This printer can be used
         for printing color transparencies for HR presentations", or "Out of
         courtesy for others, please print only small (1-5 page) jobs at this
         printer", or even "This printer is going away on July 1, 1997, please
         find a new printer".
         
         4.5.6 printer-more-info-site (uri)
         
         This attribute contains a URI used to obtain more information about
         this specific printer.  The information obtained from this URI is
         intended for end user consumption. Features outside the scope of IPP
         can be accessed from this URI.  The information is intended to be
         specific to this printer instance and site services (e.g. job pricing,
         services offered, end user assistance).  The printer manufacturer may
         initially populate this attribute.
         
         4.5.7 printer-driver-installer (uri)
         
         This attribute contains a URI to use to locate the driver installer
         for this printer.   This attribute is intended for consumption by
         automata. The mechanics of print driver installation is outside the
         scope of IPP.  The printer manufacturer may initially populate this
         attribute.
         
         4.5.8 printer-make-and-model (text)
         
         This attribute identifies the make and model of the printer.
         
         
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         4.5.9 printer-more-info-manufacturer (uri)
         
         This attribute contains a URI used to obtain more information about
         this type of printer.  The information obtained from this URI is
         intended for end user consumption.  Features outside the scope of IPP
         can be accessed from this URI (e.g., latest firmware, upgrades, print
         drivers, optional features available).  The information is intended to
         be germane to this printer without regard to site specific
         modifications or services.
         
         4.5.10 printer-state (type1 keyword)
         
         This attribute identifies the current state of the printer.  The
         "printer-state reasons" attribute augments the "printer-state"
         attribute to give more detailed information about the Printer in the
         given printer state.
         
         A Printer SHALL continually keep this attribute set to the value in
         the table below which most accurately reflects the state of the
         Printer.  A Printer NEED NOT implement all values if they are not
         applicable to a given implementation.
         
         The following standard values are defined:
         
           'unknown'(2):  The Printer state is not known, or is indeterminate.
              A Printer SHALL use this state only if it cannot determine its
              actual state.
         
           'idle'(3):  If a Printer receives a job (whose required resources
              are ready) while in this state, such a job SHALL transit into the
              processing state immediately.  If the printer-state-reasons
              attribute contains any reasons, they SHALL be reasons that would
              not prevent a job from transiting into the processing state
              immediately, e.g., toner-low. Note: if a Printer controls more
              than one output device, the above definition implies that a
              Printer is idle if at least one output device is idle.
         
           'processing'(4):  If a Printer receives a job (whose required
              resources are ready) while in this state, such a job SHALL
              transit into the pending state immediately. Such a job SHALL
              transit into the processing state only after jobs ahead of it
              complete.  If the printer-state-reasons attribute contains any
              reasons, they SHALL be reasons that do not prevent the current
              job from printing, e.g. toner-low.  Note: if a Printer controls
              more than one output device, the above definition implies that a
              Printer is processing if at least one output device is
              processing, and none is idle.
         
         
         
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           'stopped'(5):  If a Printer receives a job (whose required
              resources are ready) while in this state, such a job SHALL
              transit into the pending state immediately. Such a job SHALL
              transit into the processing state only after some human fixes the
              problem that stopped the printer and after jobs ahead of it
              complete printing.  The "printer-state-reasons" attribute SHALL
              contain at least one reason, e.g. media-jam, which prevents it
              from either processing the current job or transiting a pending
              job to the processing state.
         
              Note: if a Printer controls more than one output device, the
              above definition implies that a Printer is stopped only if all
              output devices are stopped.  Also, it is tempting to define
              stopped as when a sufficient number of output devices are stopped
              and leave it to an implementation to define the sufficient
              number.  But such a rule complicates the definition of stopped
              and processing. For example, with this alternate definition of
              stopped, a job can move from idle to processing without human
              intervention, even though the Printer is stopped.
         
         4.5.11 printer-state-reasons (1setOf type2 keyword)
         
         This attribute supplies additional detail about the printer's state.
         
         Each MAY have asuffix to indicate its level of severity.  The three
         levels are: report (least severe), warning, and error (most severe).
         
           - '-report':  This suffix indicates that the reason is a "report".
              An implementation may choose to omit some or all reports. Some
              reports specify finer granularity about the printer state; others
              serve as a precursor to a warning. A report SHALL contain nothing
              that could affect the printed output.
           - '-warning': This suffix indicates that the reason is a "warning".
              An implementation may choose to omit some or all warnings.
              Warnings serve as a precursor to an error. A warning SHALL
              contain nothing that prevents a job from completing, though in
              some cases the output may be of lower quality.
           - '-error': This suffix indicates that the reason is an "error". .
              An implementation SHALL include all errors. If this attribute
              contains one or more errors, printer SHALL be in the stopped
              state.
         
         If the implementation does not add any one of the three suffixes, all
         parties SHALL assume that the reason is an "error".
         
         If a logical Printer controls more than one output device, each value
         of this attribute MAY apply to one or more of the output devices.  An
         error on one output device that does not stop the logical Printer as a
         
         
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         whole MAY appear as a warning in the Printer's "printer-state-reasons
         attribute".  The "printer-state" for such a Printer may have a value
         of 'stopped' even though there are with no "printer-state-reasons"
         values that are "errors".
         
         The following standard values are defined:
         
           'media-needed': A tray has run out of media.
           'media-jam': The printer has a media jam.
           'paused': Someone has paused the Printer. In this state, a Printer
              SHALL not produce printed output, but it SHALL perform other
              operations requested by a client. If a Printer had been printing
              a job when the Printer was paused, the Printer SHALL resume
              printing that job when the Printer is no longer paused and leave
              no evidence in the printed output of such a pause.
           'shutdown': Someone has removed a Printer from service, and it may
              be powered down or physical removed. In this state, a Printer
              SHALL not produce printed output, and unless the Printer is
              realized by a print server that is still active, the Printer
              SHALL perform no other operations requested by a client,
              including returning this value. If a Printer had been printing a
              job when it was shutdown, the Printer need not resume printing
              that job when the Printer is no longer shutdown. If the Printer
              resumes printing such a job, it may leave evidence in the printed
              output of such a shutdown, e.g. the part printed before the
              shutdown may be printed a second time after the shutdown.
           'connecting-to-device': The server has scheduled a job on the
              Printer and is in the process of connecting to a shared network
              output device (and might not be able to actually start printing
              the job for an arbitrarily long time depending on the usage of
              the output device by other servers on the network).
           'timed-out': The server was able to connect to the output device
              (or is always connected), but was unable to get a response from
              the output device.
           'stopping': The printer will be stopping in a while and will change
              its reason to printer-stopped. This reason is a non-critical,
              even for a Printer with a single output device. When an output-
              device ceases accepting jobs, the Printer will have this state
              while the output device completes printing.
           'stopped-partly': When a Printer controls more than one output
              device, this reason indicates that one or more output devices are
              stopped. If the reason is a report, fewer than half of the output
              devices are stopped. If the reason is a warning, fewer than all
              of the output devices are stopped.
           'toner-low': The Printer is low on toner.
           'spool-area-full': The limit of persistent storage allocated for
              spooling has been reached.
         
         
         
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         4.5.12 printer-is-accepting-jobs (boolean)
         
         This attribute determines whether the printer is currently accepting
         job.  If the value is true, the printer is accepting jobs. If the
         value is false, the printer is currently rejecting any jobs submitted
         to it.
         
         Note: This value is independent of the printer state and printer-
         state-reasons because its value does not affect the current job;
         rather it affects future jobs. This attribute may cause the Printer to
         reject jobs when the printer-state is idle or it may cause the Printer
         to accepts jobs when the printer-state is stopped.
         
         4.5.13 printer-state-message (text)
         
         This attribute specifies the additional information about the printer
         state in human readable text and it SHALL be set by the Printer (or
         the Administrator by some mechanism outside the scope of IPP).
         
         4.5.14 queued-job-count (integer(0:2**31 - 1))
         
         This attribute contains a count of the number of jobs that are either
         pending and/or processing and SHALL be set by the Printer.
         
         4.5.15 printer-message-from-the-operator (text)
         
         This attribute provides a message from an operator, system
         administrator or "intelligent" process to indicate to the end user
         information or status of the printer, such as why it is unavailable or
         when it is expected to be available.
         
         4.5.16 printer-locale (locale)
         
         This attribute specifies the current locale that the Printer is
         operating in.
         
         4.5.17 printer-locales-supported (1setOf locale)
         
         This attribute specifies the supported locales that the Printer
         operates in.
         
         4.5.18 color-supported (boolean)
         
         This attribute identifies whether the Printer is capable of any type
         of color printing at all.  All document instructions having to do with
         color are embedded within the document PDL (none are external IPP
         attributes).
         
         
         
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         4.5.19 pdl-override (type2 keyword)
         
         A client supplies Job Template attributes to affect the rendering,
         production and finishing of the documents in the job.  Similar types
         of instructions may also be contained in the document to be printed,
         that is, within the Page Description Language (PDL) of the document
         data.  If there is a conflict between the value of one of these IPP
         Job Template attributes, and a corresponding instruction in the
         document (either implicit or explicit), it is desirable that the value
         of the IPP attribute take precedence over the document instruction.
         Until companies that supply interpreters for PDLs, such as PostScript
         and PCL allow a way for external attributes (such as IPP attributes)
         to take precedence over internal job production instructions, a
         Printer might not be able to support the semantics that IPP attributes
         override (take on a higher precedence) the embedded PDL instructions.
         This attribute expresses how a particular Printer implementation
         handles these conflicts.
         
         This attribute takes on the following values:
         
           - 'guaranteed': This value indicates that the Printer guarantees
              that all IPP attribute values take precedence over embedded PDL
              instructions.
           - 'attempted': This value indicates that the Printer attempts to
              make sure that IPP attribute values take precedence over embedded
              PDL instructions, however there is no guarantee.
           - 'ignored': This value indicates that the Printer ignores all IPP
              Job Template attributes and it makes no attempts to ensure that
              IPP attribute values take precedence over embedded PDL
              instructions.
         
         This is a MANDATORY attribute.
         
         Note: Since 'attempted' does not offer any type of guarantee, a given
         implementation might not do a very "good" job of attempting to ensure
         that IPP attributes take a higher precedence over PDL instructions
         embedded in the document data, but it would still be a conforming
         implementation.
         
         If the value of this attribute is 'guaranteed', the implementation
         MUST guarantee that the IPP attribute values take precedence over any
         related job processing instructions in the PDL Job's document data.
         This can be done by modifying the interpreter within the output device
         itself to understand IPP attributes, or by merging theses Job Template
         attributes directly into the document data, or in any other
         implementation specific manner.  In any case, the semantics of
         'guaranteed' MUST be preserved.
         
         
         
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         4.5.20 Security Related Attributes
         
         The security document [22] describes four common usage scenarios:
         
           - no security
           - message protection
           - client authentication and authorization
           - mutual authentication, authorization, and message protection
         
         In order to let an end user know what to expect in terms of security,
         there are two attributes described below.  Since by definition an end
         user, because of security reasons, might not be allowed to query these
         two attributes, therefore, it is important that if these two
         attributes are supported, then they are also populated in the
         directory entry (see [24]).
         
         These attributes allow for minimal client/server negotiation regarding
         security features.  If the Printer requires the feature, the client
         can decide whether or not to participate.  If the client does not
         support the feature, and the Printer requires it, then the client
         knows before hand that such an interaction would fail.
         
         Standard values for these two attributes include:
         
           'supported' -  means that the Printer is capable of supporting the
              security feature (somehow), but it is does not require the client
              to use it.
           'required' -  means that the Printer is capable of supporting the
              security feature (somehow) and the client is required to use it.
           'none' - means that the Printer is not capable of supporting
              message protection at all.
         
         Note:  This is a single-valued attribute, not a multi-valued
         attribute, i.e., an implementation can not support 'none' and
         'required' or any other combination of values.
         
         4.5.20.1 message-protection-supported (keyword)
         
         This attribute is used to determine whether or not a printer supports
         or requires message protection (whether it be through encryption or
         some other privacy mechanism).
         
         4.5.20.2 authentication-authorization-supported (keyword)
         
         This attribute is used to determine whether or not a printer supports
         or requires authentication and authorization.
         
         
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         5. Conformance
         
         This section describes conformance issues and requirements. This
         document introduces model entities such as objects, operations,
         attributes, and attribute values.  These conformance sections describe
         the conformance requirements which apply to these model entities.
         
         
         5.1 Conditionally Mandatory
         
         For example, a conditionally mandatory attribute means that a Printer
         implementation need not support the attribute if the attribute
         controls a feature that the output device does not implement or
         expose.  For example, for an output device that can only print on one
         side, a Printer need not support the "sides" attribute.  For an output
         device that does not support any of the finishing attribute values, a
         Printer need not support the "finishing" attribute.
         
         
         5.2 Client Conformance Requirements
         
         There are no conformance requirements placed on the user interfaces
         provided by IPP clients or their applications.  For example, one
         application might not allow an end user to submit multiple documents
         per job, while another does.  One application might first query a
         Printer object in order to supply a graphical user interface (GUI)
         dialogue box with supported and default values whereas a different
         implementation might not.
         
         When sending a Get-Attributes or create request, an IPP client need
         not supply any attributes.
         
         A client SHALL be able to accept any of the attribute syntaxes defined
         in Section 4.1 that may be returned to it in a response from a Printer
         
         A query response may contain attributes and values that the client
         does not expect.  Therefore, a client implementation MUST gracefully
         handle such responses and not refuse to interoperate with a conforming
         Printer that is returning extended registered or private attributes
         and/or attribute values that conform to Section 6.  Clients may choose
         to ignore any attributes that it does not understand.
         
         
         
         
         
         
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         5.3 Printer Object Conformance Requirements
         
         This section specifies the conformance requirements for conforming
         Printer object implementations with respect to objects, operations,
         and attributes.
         
         5.3.1 Objects
         
         Conforming Printer implementations SHALL implement all of the model
         objects as defined in this specification in the indicated sections:
         
           Section 2.1 Printer Object
           Section 2.2 Job Object
           Section 2.3 Document Object
         
         5.3.2 Operations
         
         Conforming Printer implementations SHALL implement all of the
         MANDATORY model operations, including mandatory responses, as defined
         in this specification in the indicated sections:
         
           For a Printer object:
              Get-Operations (section 3.1.1)               MANDATORY
              Print-Job (section 3.1.2)                    MANDATORY
              Print-URI (section 3.1.3)                    OPTIONAL
              Validate-Job (section 3.1.4)                 MANDATORY
              Create-Job (section 3.1.5)                   OPTIONAL
              Get-Jobs (section 3.1.8)                       MANDATORY
              Get-Attributes (section 3.1.9)               MANDATORY
         
           For a Job object:
              Send-Document (section 3.1.6)                OPTIONAL
              Send-URI (section 3.1.7)                     OPTIONAL
              Cancel-Job (section 3.1.8)                   MANDATORY
              Get-Attributes (section 3.1.9)               MANDATORY
         
         5.3.3 Attributes
         
         
         
         Conforming Printer implementations SHALL support all of the MANDATORY
         attributes, as defined in this specification in the indicated
         sections.
         
         Conforming Printer implementations SHALL support all CONDITIONALLY
         MANDATORY attributes as defined in this specification (in the
         indicated sections) if in the implementation the condition us true.
         
         
         
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         If a Printer implements a "xxx-supported" attribute it MUST implement
         the corresponding "xxx" default value attribute and vice versa.
         
         5.3.4 Printer extensions
         
         A conforming Printer may support registered extensions and private
         extensions, as long as they meet the requirements specified in Section
         6.
         
         5.3.5 Attribute Syntaxes
         
         A Printer SHALL be able to accept any of the attribute syntaxes
         defined in Section 4.1 in any operation in which a client may supply
         attributes or parameters.  Furthermore, a Printer SHALL return
         attributes to the client in operation responses that conform to the
         syntax specified in Section 4.1.
         
         
         5.4 Security Conformance Requirements
         
         The security mechanisms being considered for IPP fall outside the
         scope of the application layer protocol itself.  There are two
         mechanisms used to begin secure communications using IPP:
         
           1. Information in the directory entry for an IPP Printer (or from
              additional information at a Web site hosting the IPP Printer)
              indicate which, if any, security protocols are used in
              conjunction with IPP.
         
           2. The URI for the IPP Printer contains the security protocol
              information (https://..., etc.).
         
         In either case, the security protocol (if any) is initiated first
         which allows for the negotiation of security features.  IPP is then
         run as an application protocol on top of the security protocols.  One
         cannot "bootstrap" the security features from IPP itself.
         
         ISSUE: The above is not quite correct.  Waiting for better description
         from the security document [22].
         
         
         6. IANA Considerations (registered and private extensions)
         
         During the development of this standard, the IPP working group
         (working with IANA) will register additional keywords and enums while
         the standard is in the proposed and draft states according to the
         
         
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         procedures described in this section.  IANA will handle registration
         of additional enums after this standard is approved in cooperation
         with an IANA-appointed registration editor from the IPP working group
         according to the procedures described in this section.
         
         
         6.1 Typed Extensions
         
         This document identifies both keywords and enum values.  Throughout
         this document, references to "typeN enum" or "typeN keyword" can be
         found (where N can be 1, 2, 3 or 4).  The typeN extension has more
         registration controls than a typeM extension where M is greater than
         N.  That is, there are more controls in place to extend a type1 value
         over a type 2 value.  However, any typeN value MAY be registered using
         a process for some typeM where M is less than N, however such
         registration is NOT REQUIRED.  For example, a type4 value MAY be
         registered in a type1 manner (i.e., by being included in a future
         version of an IPP specification).  For private (unregistered) keyword
         extensions, implementers SHOULD use keywords with a suitable
         distinguishing prefix, such as "xxx-" where xxx is the (lowercase)
         company name registered with IANA for use in domain names.  For
         private (unregistered) enum extension, implementers SHOULD support
         values in the reserved integer range (see "enum").
         
         The definitions of these various types are as follows.
         
         6.1.1 Type1
         
         The IPP standard must be revised to add a new keyword or a new enum.
         No private keywords or enums are allowed.
         
         This draft contains the following type1 keywords:
         
           - <fill in>
         
         This draft contains the following type1 enums:
         
           - <fill in>
         
         6.1.2 Type2
         
         Implementers can, at any time, add new keyword or enum values by
         proposing them to the IPP working group for registration (or an IANA-
         appointed registry advisor after the IPP working group is no longer
         certified) where they are reviewed for approval.  IANA keeps the
         registry.
         
         This draft contains the following type2 keywords:
         
         
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           - <fill in>
         
         This draft contains the following type2 enums:
         
           - <fill in>
         
         6.1.3 Type3
         
         Implementers can, at any time, add new keyword and enum values by
         submitting a registration request directly to IANA, no IPP working
         group or IANA-appointed registry advisor review is required.
         
         This draft contains the following type3 keywords:
         
           - <fill in>
         
         This draft contains the following type3 enums:
         
           - <fill in>
         
         6.1.4 Type4
         
         Anyone (system administrators, system integrators, site managers,
         etc.) can, at any time, add new installation-defined values (keywords
         or new enum values) to a local system.  Care SHOULD be taken by the
         implementers to see that keywords do not conflict with other keywords
         defined by the standard or as defined by the implementing product.
         There is no registration or approval procedure for type4 values.
         
         This draft contains the following type4 keywords:
         
           - <fill in>
         
         This draft contains the following type4 enums:
         
           - <fill in>
         
         
         6.2 Registration of MIME types/sub-types for document-formats
         
         The "document-format" attribute has MIME type/sub-type values for
         indicating document formats which IANA registers as "media type"
         names.
         
         
         
         
         
         
         
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         7. Security Considerations
         
         There is another Internet-Draft called "Internet Printing
         Protocol/1.0: Security" [22].  That document is being drafted and
         reviewed in parallel with this document.  The mapping of IPP on top of
         appropriate security protocols will be described in that document.
         IPP does not introduce any new, general purpose security mechanisms
         for authentication and encryption.
         
         A Printer may choose, for security reasons, not to return all
         attributes that a client requests. It may even return none of the
         requested attributes. In such cases, the status returned is the same
         as if the Printer had returned all requested attributes. The client
         cannot tell by such a response whether the requested attribute was
         present or absent on the Printer.
         
         
         8. References
         
         [1]  Smith, R., Wright, F., Hastings, T., Zilles, S., and Gyllenskog,
              J., "Printer MIB", RFC 1759, March 1995.
         
         [2]  R Fielding, et al, _Hypertext Transfer Protocol _ HTTP/1.1_  RFC
              2068, January 1997
         
         [3]  Crocker, D., "Standard for the Format of ARPA Internet Text
              Messages", RFC 822, August 1982.
         
         [4]  Postel, J., "Instructions to RFC Authors", RFC 1543, October
              1993.
         
         [5]  ISO/IEC 10175 Document Printing Application (DPA), June 1996.
         
         [6]  Herriot, R. (editor), X/Open A Printing System Interoperability
              Specification (PSIS), August 1995.
         
         [7]  Kirk, M. (editor), POSIX System Administration - Part 4: Printing
              Interfaces, POSIX 1387.4 D8, 1994.
         
         [8]  Borenstein, N., and Freed, N., "MIME (Multi-purpose Internet Mail
              Extensions) Part One: Mechanism for Specifying and Describing the
              Format of Internet Message Bodies", RFC 1521, September, 1993.
         
         [9]  Braden, S., "Requirements for Internet Hosts - Application and
              Support", RFC 1123, October, 1989,
         
         [10] McLaughlin, L. III, (editor), "Line Printer Daemon Protocol" RFC
              1179, August 1990.
         
         
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         [11] Berners-Lee, T., Masinter, L., McCahill, M. , "Uniform Resource
              Locators (URL)", RFC 1738, December, 1994.
         
          [20]     Internet Printing Protocol: Requirements
         
         [21] Internet Printing Protocol/1.0: Model and Semantics (This
              document)
         
         [22] Internet Printing Protocol/1.0: Security
         
         [23] Internet Printing Protocol/1.0: Protocol Specification
         
         [24] Internet Printing Protocol/1.0: Directory Schema
         
         [25] S. Bradner, "Key words for use in RFCs to Indicate Requirement
              Levels", RFC 2119 , March 1997
         
         [26] H. Alvestrand, " Tags for the Identification of Languages", RFC
              1766, March 1995.
         
         [27] T. Hastings, "Job Monitoring MIB", <draft-ietf-print-mib-
              monitoring-01.txt>, June 1997.
         
         [28] F. Yergeau, "UTF-8, a transformation format of Unicode and ISO
              10646, RFC 2044, October 1996.
         
         [29] Turner, R. "Printer MIB", draft-ietf-printmib-mib-info-02.txt,
              July 8, 1997.  This I-D is an update to RFC 1759, March 1995 [1].
         
         [30] P. Mockapetris, "DOMAIN NAMES - IMPLEMENTATION AND
              SPECIFICATION", RFC 1035, November 1987.
         
         
         9. Author's Address
         
              Scott A. Isaacson (Editor)
              Novell, Inc.
              122 E 1700 S
              Provo, UT   84606
         
              Phone: 801-861-7366
              Fax:   801-861-4025
              EMail: scott_isaacson@novell.com
         
              Tom Hastings
              Xerox Corporation
              701 S. Aviation Blvd.
              El Segundo, CA   90245
         
         
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              Phone: 310-333-6413
              Fax:   310-333-5514
              EMail: hastings@cp10.es.xerox.com
         
              Robert Herriot
              Sun Microsystems Inc.
              2550 Garcia Ave., MPK-17
              Mountain View, CA 94043
         
              Phone: 415-786-8995
              Fax:  415-786-7077
              Email: robert.herriot@eng.sun.com
         
              Roger deBry
              HUC/003G
              IBM Corporation
              P.O. Box 1900
              Boulder, CO 80301-9191
         
              Phone: (303) 924-4080
              Fax: (303) 924-9889
              Email: debry@vnet.ibm.com
         
              Patrick Powell
              San Diego State University
              9475 Chesapeake Dr., Suite D
              San Diego, CA  95123
         
              Phone: (619) 874-6543
              Fax: (619) 279-8424
              Email: papowell@sdsu.edu
         
              IPP Mailing List:  ipp@pwg.org
              IPP Mailing List Subscription:  ipp-request@pwg.org
              IPP Web Page:  http://www.pwg.org/ipp/
         
           Other Participants:
         
              Chuck Adams - Tektronix
              Jeff Barnett - IBM
              Ron Bergman - Data Products
              Keith Carter, IBM Corporation
              Jeff Copeland - QMS
              Andy Davidson - Tektronix
              Mabry Dozier - QMS
              Lee Farrell - Canon Information Systems
              Steve Gebert - IBM
         
         
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              David Kellerman - Northlake Software
              Rick Landau - Digital
              Harry Lewis - IBM
              Pete Loya - HP
              Ray Lutz - Cognisys
              Mike MacKay, Novell, Inc.
              Carl-Uno Manros, Xerox, Corp.
              Jay Martin - Underscore
              Stan McConnell - Xerox
              Pat Nogay - IBM
              Bob Pentecost - HP
              Rob Rhoads - Intel
              David Roach - Unisys
              Hiroyuki Sato - Canon
              Bob Setterbo - Adobe
              Devon Taylor, Novell, Inc.
              Mike Timperman - Lexmark
              Randy Turner - Sharp
              Atsushi Yuki - Kyocera
              Lloyd Young - Lexmark
              Bill Wagner - DPI
              Jim Walker - DAZEL
              Chris Wellens - Interworking Labs
              Rob Whittle - Novell
              Don Wright - Lexmark
              Peter Zehler, Xerox, Corp.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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         10. APPENDIX A: Terminology
         
         This specification uses the terminology defined in this section.
         
         
         10.1 Conformance Terminology
         
         The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
         "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and  "OPTIONAL" in this
         document are to be interpreted as described in RFC 2119 [25].
         
         10.1.1 MUST
         
         This word, or the terms "REQUIRED",  "SHALL" or "MANDATORY", means
         that the definition is an absolute requirement of the specification.
         
         10.1.2 MUST NOT
         
         This phrase, or the phrase "SHALL NOT", means that the definition is
         an absolute prohibition of the specification.
         
         10.1.3 SHOULD
         
         This word, or the adjective "RECOMMENDED", means that there may exist
         valid reasons in particular circumstances to ignore a particular item,
         but the full implications must be understood and carefully weighed
         before choosing a different course.
         
         10.1.4 SHOULD NOT
         
         This phrase, or the phrase "NOT RECOMMENDED" means that there may
         exist valid reasons in particular circumstances when the particular
         behavior is acceptable or even useful, but the full implications
         should be understood and the case carefully weighed before
         implementing any behavior described with this label.
         
         10.1.5 MAY
         
         This word, or the adjective "OPTIONAL", means that an item is truly
         optional.  One vendor may choose to include the item because a
         particular marketplace requires it or because the vendor feels that it
         enhances the product while another vendor may omit the same item.   An
         implementation which does not include a particular option MUST be
         prepared to interoperate with another implementation which does
         include the option, though perhaps with reduced functionality. In the
         same vein an implementation which does include a particular option
         MUST be prepared to interoperate with another implementation which
         
         
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         does not include the option (except, of course, for the feature the
         option provides.)
         
         10.1.6 CONDITIONALLY MANDATORY
         
         This term means that an item MUST be implemented in a conforming
         implementation if the specified condition is true.  Conversely, a
         conforming implementation NEED NOT implement the item if the specified
         condition is false.
         
         10.1.7 NEED NOT
         
         The verb "NEED NOT" indicates an action that the subject of the
         sentence does not have to implement in order to claim conformance to
         the standard.  The verb "NEED NOT" is used instead of "MAY NOT" since
         "MAY NOT" sounds like a prohibition.
         
         
         10.2 Model Terminology
         
         10.2.1 Keyword
         
         Keywords are used within this document as identifiers of semantic
         entities within the abstract model.  Attribute names, some attribute
         values, attribute syntaxes, and attribute group names are represented
         as keywords.  In this document, a keyword is a sequence of characters
         (length of 1 to 255) which consists of the following ASCII characters:
         lower-case letters ("a" - "z"), digits ("0" - "9"), hyphen ("-"), and
         underscore ("_").  A keyword starts with a lower-case letter.  In the
         actual protocol, these keywords will be represented using an
         appropriate protocol encoding.
         
         10.2.2 Parameters
         
         A parameter is an item of information supplied in an operation
         consisting of a parameter name and a parameter value(s).  Each
         parameter has a specific syntax. Clients supply input parameters in
         operation requests and servers return output parameters in operation
         responses.  Most parameters have corresponding object attributes; some
         do not.  All parameters are defined in section 3.
         
         10.2.2.1 Parameter Name
         
         Each parameter is uniquely identified in this document by its
         parameter name which is a keyword.  The keyword parameter name is
         given in the section header describing that parameter.  In running
         text in this document, parameter names are indicated inside double
         quotation marks (").
         
         
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         10.2.2.2 Parameter Value
         
         Each parameter has one or more values.  Parameter values are
         represented in the syntax type specified for that parameter. In
         running text in this document, parameter values are indicated inside
         single quotation marks ('), whether their parameter syntax is keyword,
         integer, text, etc.
         
         10.2.2.3 Parameter Syntax
         
         Each parameter is defined using an explicit syntax.  In this document,
         each syntax type is defined as a keyword with specific meaning.  The
         protocol specification document [23] indicates the actual on-the-wire
         encoding for each parameter syntax. Parameter syntaxes are the same as
         attribute syntaxes and they are defined in section 4.1.
         
         10.2.3 Attributes
         
         An attribute is an item of information that is associated with an
         instance of an IPP object.  An attribute consists of an attribute name
         and an attribute value(s).  Each attribute has a specific syntax..
         All attributes are defined in section 4.
         
         An interesting set of attributes is called Job Template Attributes
         (these attributes are described in detail in section 4.2.)  The client
         optionally supplies Job Template attributes as input parameters in a
         create request (operation requests that create Job objects).  The
         Printer object has associated attributes which define supported and
         default values for the Printer.  Thee following rules apply:
         
           - When a Job Template attribute is supplied as an input parameter
              in a create request, the attribute and its value describe the
              desired job processing behavior.
         
           - The Printer object's supported attribute describes what behaviors
              are possible.
         
           - The Printer object's default value attribute describes what will
              be done when no other job processing information is supplied by
              the client.
         
         10.2.3.1 Attribute Name
         
         Each attribute is uniquely identified in this document by its
         attribute name which is a keyword.  The keyword attribute name is
         given in the section header describing that attribute.  In running
         text in this document, attribute names are indicated inside double
         quotation marks (").
         
         
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         10.2.3.2 Attribute Group Name
         
         Related attributes are grouped into named groups.  The name of the
         group is a keyword.  The group name may be used in an input parameter
         in place of naming all the attributes in the group explicitly.
         Attribute groups are defined in section 4.
         
         10.2.3.3 Attribute Value
         
         Each attribute has one or more values.  Attribute values are
         represented in the syntax type specified for that attribute. In
         running text in this document, attribute values are indicated inside
         single quotation marks ('), whether their attribute syntax is keyword,
         integer, text, etc.
         
         10.2.3.4 Attribute Syntax
         
         Each attribute is defined using an explicit attribute syntax.  In this
         document, each attribute syntax is defined as a keyword with specific
         meaning.  The protocol specification document [23] indicates the
         actual on-the-wire encoding for each attribute syntax. Attribute
         syntaxes are defined in section 4.1.
         
         10.2.4 Supports
         
         By definition, an implementation (an instance of an IPP object)
         supports an attribute (or a particular value of an attribute) only if
         that implementation responds with the corresponding attribute and
         value in a response to a query for that attribute.  A given
         implementation may exhibit a behavior that corresponds to the value of
         some attribute, but if the implementation, when queried for that
         attribute, doesn't respond with the supported attribute populated with
         that specific value, then as far as IPP is concerned, that
         implementation does not support that feature.
         
         A conforming implementation SHALL support all MANDATORY attributes and
         all CONDITIONALLY MANDATORY attributes where the implementation
         satisfies the condition associated with the CONDITIONALLY MANDATORY
         attribute.  Conformance to IPP does not mandate that all
         implementations support all possible values representing all possible
         job processing behaviors and features.  For example, if a given
         instance of a Printer supports only certain document formats, then
         that Printer responds with the "document-format-supported" attribute
         populated with a set of values, possibly only one, taken from the
         entire set of possible values defined in this model document.  This
         set of values represent the Printer's set of supported document
         formats.  Another example is the "finishings-supported" attribute.  If
         a Printer is not physically capable of stapling (there is no stapler
         
         
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         in the output device itself), the "finishings-supported" attribute
         MUST NOT be populated with the value of 'staple'.
         
         In order to ease the implementation burden, if a certain
         implementation supports only one well-known value of some "xxx-
         supported" attribute, it is NOT REQUIRED that that implementation
         support that attribute.  For example, if a Printer object represents a
         physical device that can not print on two sides of the media, the only
         possible value for the "sides-supported" attribute could be 'one-
         sided'.  In this case, it is NOT REQUIRED that the implementation
         support the "sides-supported" attribute since a client could infer
         that the implementation supports only single-sided printing from the
         absence of the "sides-supported" attribute.  If for some reason, an
         implementation only supported "two-sided-long-edge" then that
         implementation MUST support the "sides-supported" attribute to be a
         conforming implementation.  The "well-known value" for CONDITIONALLY
         MANDATORY attribute is specified in the section describing that
         attribute.
         
         Note: The supported attributes are set (populated) by some
         administrative process or automatic sensing mechanism that  is outside
         the scope of IPP.
         
         
         11. APPENDIX B:  Status Codes
         
         This section defines status code keywords that are used to provide
         semantic information on the results of an operation request.  Each
         operation response MUST include a status code.  For error type status
         codes, the response MAY also contain a message that provides a short
         textual description of the status. The status code is intended for use
         by automata, and the message is intended for the human end user.
         Since the message is an OPTIONAL component of the operation response,
         an IPP application (i.e. a browser, GUI, print driver or gateway) is
         NOT REQUIRED to examine or display the message.
         
         The prefix of the status keyword defines the class of response as
         follows:
         
           "informational" - Request received, continuing process
           "successful" - The action was successfully received, understood,
              and accepted
           "redirection" - Further action must be taken in order to complete
              the request
           "client-error" - The request contains bad syntax or cannot be
              fulfilled
           "server-error" - The server failed to fulfill an apparently valid
              request
         
         
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         IPP status codes are extensible.  IPP applications are NOT REQUIRED to
         understand the meaning of all registered status codes, though such
         understanding is obviously desirable.  However, applications SHALL
         understand the class of any status code, as indicated by the prefix,
         and treat any unrecognized response as being equivalent to the first
         status code of that class, with the exception that an unrecognized
         response shall not be cached.  For example, if an unrecognized status
         code of "client-error-foo-bar" is received by the client, it can
         safely assume that there was something wrong with its request and
         treat the response as if it had received a "client-error-bad-request"
         status code.  In such cases, IPP applications could present the
         OPTIONAL message (if present) to the end user since the message is
         likely to contain human readable information which will help to
         explain the unusual status.
         
         
         11.1 Status Codes (type2 keyword)
         
         Each status code is described below. Section 11.2 contains a table
         that indicates which status codes apply to which operations.
         
         11.1.1 Informational
         
         This class of status code indicates a provisional response and is to
         be used for informational purposes only.
         
         There are no status codes defined in IPP 1.0 for this class of status
         code.
         
         11.1.2 Successful Status Codes
         
         This class of status code indicates that the client's request was
         successfully received, understood, and accepted.
         
         11.1.2.1 successful-ok
         
         The request has succeeded.
         
         11.1.3 Redirection Status Codes
         
         This class of status code indicates that further action needs to be
         taken to fulfill the request.
         
         There are no status codes defined in IPP 1.0 for this class of status
         code.
         
         
         
         
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         11.1.4 Client Error Status Codes
         
         This class of status code is intended for cases in which the client
         seems to have erred.  The server SHOULD return a message containing an
         explanation of the error situation and whether it is a temporary or
         permanent condition.
         
         11.1.4.1 client-error-bad-request
         
         The request could not be understood by the server due to malformed
         syntax.  The IPP application SHOULD NOT repeat the request without
         modifications.
         
         
         
         11.1.4.2 client-error-forbidden
         
         The server understood the request, but is refusing to fulfill it.
         Additional authentication information or authorization credentials
         will not help and the request SHOULD NOT be repeated.  This status
         code is commonly used when the server does not wish to reveal exactly
         why the request has been refused or when no other response is
         applicable.
         
         11.1.4.3 client-error-not-authenticated
         
         The request requires user authentication.  The IPP client may repeat
         the request with suitable authentication information. If the request
         already included authentication information, then this status code
         indicates that authorization has been refused for those credentials.
         If this response contains the same challenge as the prior response,
         and the user agent has already attempted authentication at least once,
         then the response message may contain relevant diagnostic information.
         This status codes reveals more information than "client-error-
         forbidden".
         
         11.1.4.4 client-error-not-authorized
         
         The requester is not authorized to perform the request.  Additional
         authentication information or authorization credentials will not help
         and the request SHOULD be repeated.  This status code is used when the
         server wishes to reveal that the authentication information is
         understandable, however, the requester is explicitly not authorized to
         perform the request.  This status codes reveals more information than
         "client-error-forbidden".
         
         
         
         
         
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         11.1.4.5 client-error-not-possible
         
         This status code is used when the request is for something that can
         happen.  For example, there might be a request to cancel a job that
         has already been aborted by the system.  The IPP client SHOULD NOT
         repeat the request.
         
         11.1.4.6 client-error-timeout
         
         The client did not produce a request within the time that the server
         was prepared to wait.  For example, a client issued a Create-Job
         operation and then, after a long period of time, issued a Send-
         Document operation and this error status code was returned in response
         to the Send-Document request.  The server might have been forced to
         clean up resources that had been held for the waiting additional
         Documents.  The server was forced to close the Job since the client
         took too long.  The client SHOULD NOT repeat the request without
         modifications.
         
         11.1.4.7 client-error-not-found
         
         The server has not found anything matching the request URI.  No
         indication is given of whether the condition is temporary or
         permanent.  For example, a client with an old reference to a Job (a
         URI) tries to cancel the Job, however in the mean time the Job might
         have been completed and all record of it at the Printer has been
         deleted.  This status code, 'client-error-not-found' is returned
         indicating that the referenced Job can not be found.  This error
         status code is also used when a client supplies a URI as a reference
         to the document data in either a Print-URI or Send-URI operation
         however the document can not be found.
         
         ISSUE: Shall a printer be required to validate the URI at submit time?
         If the Printer tries to resolve the URI at job processing time, how is
         this error returned?  In a new "job-state-reasons" value?  In a "job-
         state-message" value?
         
         In practice, an IPP application should avoid a not found situation by
         first querying and presenting a list of valid Printer URIs and Job
         URIs to the end-user.
         
         11.1.4.8 client-error-gone
         
         The requested object is no longer available at the server and no
         forwarding address is known.  This condition should be considered
         permanent.  Clients with link editing capabilities should delete
         references to the request URI after user approval.  If the server does
         not know or has no facility to determine, whether or not the condition
         
         
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         is permanent, the status code "client-error-not-found" should be used
         instead.
         
         This response is primarily intended to assist the task of web
         maintenance by notifying the recipient that the resource is
         intentionally unavailable and that the server owners desire that
         remote links to that resource be removed. It is not necessary to mark
         all permanently unavailable resources as "gone" or to keep the mark
         for any length of time -- that is left to the discretion of the server
         owner.
         
         11.1.4.9 client-error-request-entity-too-large
         
         The server is refusing to process a request because the request entity
         is larger than the server is willing or able to process.  An IPP
         Printer returns this status code when it limits the size of print jobs
         and it receives a print job that exceeds that limit or when the
         operation parameters are so many that their encoding causes the
         request entity to exceed server capacity.
         
         11.1.4.10 client-error-request-URI-too-long
         
         The server is refusing to service the request because the request URI
         is longer than the server is willing to interpret.  This rare
         condition is only likely to occur when a client has improperly
         submitted a request with long query information (e.g. an IPP
         application allows an end-user to enter an invalid URI), when the
         client has descended into a URI "black hole" of redirection (e.g., a
         redirected URI prefix that points to a suffix of itself), or when the
         server is under attack by a client attempting to exploit security
         holes present in some servers using fixed-length buffers for reading
         or manipulating the Request-URI.
         
         11.1.4.11 client-error-unsupported-document-format
         
         The server is refusing to service the request because the print data
         is in a format, as specified in the "document-format" input parameter,
         that is not supported by the IPP Printer.
         
         11.1.4.12 client-error-attribute- not-supported
         
         For a Create-Job, Print-Job or Validate operation, if the IPP Printer
         does not support at least one attribute or one attribute value
         supplied in the request, the Printer shall return this status.  For
         example, if the request requires A4 paper and that paper size is not
         supported by the Printer, the Printer shall return this status.
         
         
         
         
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         For a Get-Jobs operation, if the IPP Printer does not support one of
         the requested attributes, , the Printer shall return this status.
         
         In practice, an IPP application should avoid this situation by
         querying an IPP Printer for its valid attributes and values before
         performing an operation on the Printer.
         
         11.1.5 Server Error Status Codes
         
         This class of status codes indicates cases in which the server is
         aware that it has erred or is incapable of performing the request.
         The server SHOULD include a message containing an explanation of the
         error situation, and whether it is a temporary or permanent condition.
         
         11.1.5.1 server-error-internal- error
         
         The server encountered an unexpected condition that prevented it from
         fulfilling the request.  This error status code differs from "server-
         error-temporary-error" in that it implies a more permanent type of
         internal error.  It also differs from "server-error-device-error" in
         that it implies an unexpected condition (unlike a paper-jam or out-of-
         toner problem which is undesirable but expected).  This error status
         code indicates that probably some knowledgeable human intervention is
         required.
         
         11.1.5.2 server-error-operation-not-supported
         
         The server does not support the functionality required to fulfill the
         request. This is the appropriate response when the server does not
         recognize an operation or is not capable of supporting it.
         
         11.1.5.3 server-error-service-unavailable
         
         The server is currently unable to handle the request due to a
         temporary overloading or maintenance of the server.  The implication
         is that this is a temporary condition which will be alleviated after
         some delay. If known, the length of the delay may be indicated in the
         message.  If no delay is given, the IPP application should handle the
         response as it would for a "server-error-temporary-internal-error"
         response.  If the condition is more permanent, the error status codes
         "client-error-gone" or "client-error-not-found" could be used.
         
         11.1.5.4 server-error- version-not-supported
         
         The server does not support, or refuses to support, the IPP protocol
         version that was used in the request message.  The server is
         indicating that it is unable or unwilling to complete the request
         using the same version as supplied in the request other than with this
         
         
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         error message. The response should contain a Message describing why
         that version is not supported and what other versions are supported by
         that server.
         
         A conforming IPP client shall specify the valid version (IPP 1.0)on
         each request.  A conforming IPP server (IPP 1.0) SHALL NOT return this
         status code to a conforming IPP 1.0 client.  An IPP server shall
         return this status code to a non-conforming IPP client.
         
         11.1.5.5 server-error-device-error
         
         A printer error, such as a paper jam, occurs while the IPP Printer
         processes a Print or Send operation.  The response contains the true
         Job Status (the values of the "job-state" and "job-state-reasons"
         attributes).  Additional information can be returned in the optional
         "job-state-message" attribute value or in the OPTIONAL status code
         message that describes the error in more detail.  This error status
         code MAY be returned even though the operation was successful (the Job
         was submitted and is now in the 'pending' state waiting to be
         processed).
         
         11.1.5.6 server-error-temporary-error
         
         A temporary error such as a buffer full write error, a memory overflow
         (i.e. the document data exceeds the memory of the Printer), or a disk
         full condition, occurs while the IPP Printer processes an operation.
         The client MAY try the unmodified request again at some later point in
         time with an expectation that the temporary internal error condition
         may have been cleared.
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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         11.2 Status Keywords for IPP Operations
         
         PJ = Print-Job, PU = Print-URI, CJ = Create-Job, SD = Send-Document
         SU = Send-URI, V = Validate, GA = Get-Attributes, GJ = Get-Jobs
         GO = Get-Operations, C = Cancel-Job
         
                                                        IPP Operations
         IPP Status Keyword                       PJ PU CJ SD SU V GA GJ GO C
         ------------------                       -- -- -- -- -- - -- -- -- -
         successful-OK                            x  x  x  x  x  x x  x  x  x
         client-error-bad-request                 x  x  x  x  x  x x  x  x  x
         client-error-not-authenticated           x  x  x  x  x  x x  x  x  x
         client-error-not-authorized              x  x  x  x  x  x x  x  x  x
         client-error-forbidden                   x  x  x  x  x  x x  x  x  x
         client-error-not-possible                x  x  x  x  x  x x  x  x  x
         client-error-not-found                   x  x  x  x  x  x x  x  x  x
         client-error-timeout                     x  x  x  x  x  x x  x  x  x
         client-error-gone                        x  x  x  x  x  x x  x  x  x
         client-error-request-entity-too-large    x  X  X  X  X  X X  X  X  X
         client-error-request-URI-too-long        x  x  x  x  x  x x  x  x  x
         client-error-unsupported-document-format x  x     x  x
         client-error-attribute-value-not-        x  x  x        x
              supported
         server-error-internal-error       x  x  x  x  x  x x  x  x  x
         server-error-service-unavailable         x  x  x  x  x  x x  x  x  x
         server-error-timeout                     x  x  x  x  x  x x  x  x  x
         server-error-HTTP-version-not-supported  x  x  x  x  x  x x  x  x  x
         server-error-IPP-version-not-supported   x  x  x  x  x  x x  x  x  x
         server-error-device-error                x  x  x  x  x
         server-error-temporary-error             x  x  x  x  x
         
         
         12. APPENDIX C: "document-format" enum values
         
         The Printer Working Group has registered a set of type2 enum values
         with IANA as part of the IETF Printer MIB [1] project.  The standard
         value assigned by the PWG starts with the four letters: "lang", in
         order to follow SNMP ASN.1 rules that all enum symbols SHALL start
         with a lower case letter. The integer enum value is used as the value
         the "document-format" attribute.
         
         This APPENDIX lists the document formats that are currently registered
         with IANA.  As with all type 2 and type 3 enums, when additional enum
         values are registered with IANA, they may be used in IPP withhout
         updating this appendix.
         
         ISSUE: PDF does not have an enum value, though it has a MIME type.
         Adobe needs to register PDF as one of the standard values.
         
         
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         The standard values registered at the current time are:
         
           'other': 1 -
           'langPCL': 3 - PCL.  Starting with PCL version 5, HP-GL/2 is
              included as part of the PCL language.  PCL and HP-GL/2 are
              registered trademarks of Hewlett-Packard Company.
           'langHPGL': 4 - Hewlett-Packard Graphics Language.  HP-GL is a
              registered trademark of Hewlett-Packard Company.
           'langPJL': 5 - Peripheral Job Language.  Appears in the data stream
              between data intended for a page description language.  Hewlett-
              Packard Co.
           'langPS': 6 - PostScript Language (tm) Postscript - a trademark of
              Adobe Systems Incorporated which may be registered in certain
              jurisdictions
           'langIPDS': 7 - Intelligent Printer Data Stream Bi-directional
              print data stream for documents consisting of data objects (text,
              image, graphics, bar codes), resources (fonts, overlays) and
              page, form and finishing instructions.  Facilitates system level
              device control, document tracking and error recovery throughout
              the print process.  Pennant Systems, IBM
           'langPPDS': 8 - IBM Personal Printer Data Stream.  Originally
              called IBM ASCII, the name was changed to PPDS when the Laser
              Printer was introduced in 1989.  Lexmark International, Inc.
           'langEscapeP': 9 - Epson Corp.
           'langEpson': 10 -
           'langDDIF': 11 - Digital Document Interchange Format Digital
              Equipment Corp., Maynard MA
           'langInterpress': 12 - Xerox Corp.
           'langISO6429': 13 - ISO 6429.  Control functions for Coded
              Character Sets (has ASCII control characters, plus additional
              controls for character imaging devices.) ISO Standard, Geneva,
              Switzerland
           'langLineData': 14 - line-data: Lines of data as separate ASCII or
              EBCDIC records and containing no control functions (no CR, LF,
              HT, FF, etc.).  For use with traditional line printers.  May use
              CR and/or LF to delimit lines, instead of records.  See ISO 10175
              Document Printing Application (DPA) ISO standard, Geneva,
              Switzerland
           'langMODCA': 15 - Mixed Object Document Content Architecture
              Definitions that allow the composition, interchange, and
              presentation of final form documents as a collection of data
              objects (text, image, graphics, bar codes), resources (fonts,
              overlays) and page, form and finishing instructions.  Pennant
              Systems, IBM
           'langREGIS': 16 - Remote Graphics Instruction Set, Digital
              Equipment Corp., Maynard MA
           'SCS': 17 - SNA Character String Bi-directional print data stream
              for SNA LU-1 mode of communications IBM
         
         
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           'langSPDL': 18 - ISO 10180 Standard Page Description Language ISO
              Standard
           'langTEK4014': 19 - Tektronix Corp.
           'langPDS': 20 -
           'langIGP': 21 - Printronix Corp.
           'langCodeV': 22 - Magnum Code-V, Image and printer control language
              used to control impact/dot- matrix printers.  QMS, Inc., Mobile
              AL
           'langDSCDSE': 23 - DSC-DSE: Data Stream Compatible and Emulation
              Bi-directional print data stream for non-SNA (DSC) and SNA LU-3
              3270 controller (DSE) communications IBM
           'langWPS': 24 - Windows Printing System, Resource based
              command/data stream used by Microsoft At Work Peripherals.
              Developed by the Microsoft Corporation.
           'langLN03': 25 - Early DEC-PPL3, Digital Equipment Corp.
           'langCCITT': 26 -
           'langQUIC': 27 - QUIC (Quality Information Code), Page Description
              Language for laser printers.  Included graphics, printer control
              capability and emulation of other well- known printer .  QMS,
              Inc.
           'langCPAP': 28 - Common Printer Access Protocol Digital Equipment
              Corp
           'langDecPPL': 29 - Digital ANSI-Compliant Printing Protocol (DEC-
              PPL) Digital Equipment Corp
           'langSimpleText': 30 - simple-text: character coded data, including
              NUL, CR , LF, HT, and FF control characters.  See ISO 10175
              Document Printing Application (DPA) ISO standard, Geneva,
              Switzerlan
           'langNPAP': 31 - Network Printer Alliance Protocol (NPAP).  This
              protocol has been superseded by the IEEE 1284.1 TIPSI standard.
              (ref.  LangTIPSI(49)).
           'langDOC': 32 - Document Option Commands, Appears in the data
              stream between data intended for a page description .  QMS, Inc
           'langimPress': 33 - imPRESS, Page description language originally
              developed for the ImageServer line of systems.  A binary language
              providing representations for text, simple graphics (rules,
              lines, conic sections), and some large forms (simple bit-map and
              CCITT group 3/4 encoded).The language was intended to be sent
              over an 8-bit channel and supported early document preparation
              languages (e.g.  TeX and TROFF).  QMS, Inc.
           'langPinwriter': 34 - 24 wire dot matrix printer for USA, Europe,
              and Asia except Japan.  More widely used in Germany, and some
              Asian countries than in US.  NEC
           'langNPDL': 35 - Page printer for Japanese market.  NEC
           'langNEC201PL': 36 - Serial printer language used in the Japanese
              market.  NEC
           'langAutomatic': 37 - Automatic PDL sensing.  Automatic sensing of
              the interpreter language family by the printer examining the
         
         
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              document content.  Which actual interpreter language families are
              sensed depends on the printer implementation.
           'langPages': 38 - Page printer Advanced Graphic Escape Set IBM
              Japan
           'langLIPS': 39 - LBP Image Processing System
           'langTIFF': 40 - Tagged Image File Format (Aldus)
           'langDiagnostic': 41 - A hex dump of the input to the interpreter
           'langPSPrinter': 42 - The PostScript Language used for control
              (with any PDLs) Adobe Systems Incorporated
           'langCaPSL': 43 - Canon Print Systems Language
           'langEXCL': 44 - Extended Command Language Talaris Systems Inc
           'langLCDS': 45 - Line Conditioned Data Stream Xerox Corporatio
           'langXES': 46 - Xerox Escape Sequences Xerox Corporation
           'langPCLXL': 47 - Printer Control Language.  Extended language
              features for printing, and printer control.  Technical reference
              manual # TBD.  Hewlett-Packard Co.
           'langART': 48 - Advanced Rendering Tools (ART).  Page Description
              language originally developed for the Laser Press printers.
              Tehnical reference manual: "ART IV Reference Manual", No F33M.
              Fuji Xerox Co., Ltd.
           'langTIPSI': 49 - Transport Independent Printer System Interface
              (ref.  IEEE Std.  1284.1)
           'langPrescribe': 50 - Page description and printer control
              language.  It can be described with ordinary ASCII characters.
              Technical reference manual: "PRESCRIBE II Programming Manual"
           'langLinePrinter': 51 - A simple-text character stream which
              supports the control codes LF, VT, FF and CR plus Centronics or
              Dataproducts Vertical Format Unit (VFU).  language is commonly
              used on many older model line and matrix printers.
           'langIDP': 52 - Imaging Device Protocol Apple Computer.
           'langXJCL': 53 - Xerox Corp.
         
         
         One special value is 'langAutomatic (37)'.  However a client SHALL NOT
         supply the value 'langAutomatic' in a create request.  If the
         "document-format" is unknown for a certain document, the client SHALL
         NOT supply the attribute in the create request or the Send-Document
         Request.
         
         
         13. APPENDIX D:  "media" keyword values
         
         Standard keyword values are taken from several sources.
         
         Standard values are defined (taken from ISO DPA[5] and the Printer
         MIB[1]):
         
           'default': The default medium for the output device
         
         
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           'iso-a4-white': Specifies the ISO A4 white medium
           'iso-a4-colored': Specifies the ISO A4 coloured medium
           'iso-a4-transparent' Specifies the ISO A4 transparent medium
           'iso-a3-white': Specifies the ISO A3 white medium
           'iso-a3-colored': Specifies the ISO A3 coloured medium
           'iso-a5-white': Specifies the ISO A5 white medium
           'iso-a5-colored': Specifies the ISO A5 coloured medium
           'iso-b4-white': Specifies the ISO B4 white medium
           'iso-b4-colored': Specifies the ISO B4 coloured medium
           'iso-b5-white': Specifies the ISO B5 white medium
           'iso-b5-colored': Specifies the ISO B5 coloured medium
           'jis-b4-white': Specifies the JIS B4 white medium
           'jis-b4-colored': Specifies the JIS B4 coloured medium
           'jis-b5-white': Specifies the JIS B5 white medium
           'jis-b5-colored': Specifies the JIS B5 coloured medium
         
         
         The following standard values are defined for North American media:
         
           'na-letter-white': Specifies the North American letter white medium
           'na-letter-colored': Specifies the North American letter coloured
              medium
           'na-letter-transparent': Specifies the North American letter
              transparent medium
           'na-legal-white': Specifies the North American legal white medium
           'na-legal-colored': Specifies the North American legal coloured
              medium
         
         
         The following standard values are defined for envelopes:
         
           'iso-b4-envelope': Specifies the ISO B4 envelope medium
           'iso-b5-envelope': Specifies the ISO B5 envelope medium
           'iso-c3-envelope': Specifies the ISO C3 envelope medium
           'iso-c4-envelope': Specifies the ISO C4 envelope medium
           'iso-c5-envelope': Specifies the ISO C5 envelope medium
           'iso-c6-envelope': Specifies the ISO C6 envelope medium
           'iso-designated-long-envelope': Specifies the ISO Designated Long
              envelope medium
           'na-10x13-envelope': Specifies the North American 10x13 envelope
              medium
           'na-9x12-envelope': Specifies the North American 9x12 envelope
              medium
           'monarch-envelope': Specifies the Monarch envelope
           'na-number-10-envelope': Specifies the North American number 10
              business envelope medium
           'na-7x9-envelope': Specifies the North American 7x9 inch envelope
           'na-9x11-envelope': Specifies the North American 9x11 inch envelope
         
         
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           'na-10x14-envelope': Specifies the North American 10x14 inch
              envelope
           'na-number-9-envelope': Specifies the North American number 9
              business envelope
           'na-6x9-envelope': Specifies the North American 6x9 inch envelope
           'na-10x15-envelope': Specifies the North American 10x15 inch
              envelope
         
         
         The following standard values are defined for the less commonly used
         media (white-only):
         
           'executive-white': Specifies the white executive medium
           'folio-white': Specifies the folio white medium
           'invoice-white': Specifies the white invoice medium
           'ledger-white': Specifies the white ledger medium
           'quarto-white': Specified the white quarto medium
           'iso-a0-white': Specifies the ISO A0 white medium
           'iso-a1-white': Specifies the ISO A1 white medium
           'iso-a2-white': Specifies the ISO A2 white medium
           'iso-a6-white': Specifies the ISO A6 white medium
           'iso-a7-white': Specifies the ISO A7 white medium
           'iso-a8-white': Specifies the ISO A8 white medium
           'iso-a9-white': Specifies the ISO A9 white medium
           'iso-10-white': Specifies the ISO A10 white medium
           'iso-b0-white': Specifies the ISO B0 white medium
           'iso-b1-white': Specifies the ISO B1 white medium
           'iso-b2-white': Specifies the ISO B2 white medium
           'iso-b3-white': Specifies the ISO B3 white medium
           'iso-b6-white': Specifies the ISO B6 white medium
           'iso-b7-white': Specifies the ISO B7 white medium
           'iso-b8-white': Specifies the ISO B8 white medium
           'iso-b9-white': Specifies the ISO B9 white medium
           'iso-b10-white': Specifies the ISO B10 white medium
           'jis-b0-white': Specifies the JIS B0 white medium
           'jis-b1-white': Specifies the JIS B1 white medium
           'jis-b2-white': Specifies the JIS B2 white medium
           'jis-b3-white': Specifies the JIS B3 white medium
           'jis-b6-white': Specifies the JIS B6 white medium
           'jis-b7-white': Specifies the JIS B7 white medium
           'jis-b8-white': Specifies the JIS B8 white medium
           'jis-b9-white': Specifies the JIS B9 white medium
           'jis-b10-white': Specifies the JIS B10 white medium
         
         
         The following standard values are defined for engineering media:
         
           'a': Specifies the engineering A size medium
         
         
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           'b': Specifies the engineering B size medium
           'c': Specifies the engineering C size medium
           'd': Specifies the engineering D size medium
           'e': Specifies the engineering E size medium
         
         
         The following standard values are defined for input-trays (from ISO
         DPA and the Printer MIB):
         
           'top': The top input tray in the printer.
           'middle': The middle input tray in the printer.
           'bottom': The bottom input tray in the printer.
           'envelope': The envelope input tray in the printer.
           'manual': The manual feed input tray in the printer.
           'large-capacity': The large capacity input tray in the printer.
           'main': The main input tray
           'side': The side input tray
         
         
         The following standard values are defined for media sizes (from ISO
         DPA):
         
           'iso-a0': Specifies the ISO A0 size: 841 mm by 1189 mm as defined
              in ISO 216
           'iso-a1': Specifies the ISO A1 size: 594 mm by 841 mm as defined in
              ISO 216
           'iso-a2': Specifies the ISO A2 size: 420 mm by 594 mm as defined in
              ISO 216
           'iso-a3': Specifies the ISO A3 size: 297 mm by 420 mm as defined in
              ISO 216
           'iso-a4': Specifies the ISO A4 size: 210 mm by 297 mm as defined in
              ISO 216
           'iso-a5': Specifies the ISO A5 size: 148 mm by 210 mm as defined in
              ISO 216
           'iso-a6': Specifies the ISO A6 size: 105 mm by 148 mm as defined in
              ISO 216
           'iso-a7': Specifies the ISO A7 size: 74 mm by 105 mm as defined in
              ISO 216
           'iso-a8': Specifies the ISO A8 size: 52 mm by 74 mm as defined in
              ISO 216
           'iso-a9': Specifies the ISO A9 size: 37 mm by 52 mm as defined in
              ISO 216
           'iso-a10': Specifies the ISO A10 size: 26 mm by 37 mm as defined in
              ISO 216
           'iso-b0': Specifies the ISO B0 size: 1000 mm by 1414 mm as defined
              in ISO 216
           'iso-b1': Specifies the ISO B1 size: 707 mm by 1000 mm as defined
              in ISO 216
         
         
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           'iso-b2': Specifies the ISO B2 size: 500 mm by 707 mm as defined in
              ISO 216
           'iso-b3': Specifies the ISO B3 size: 353 mm by 500 mm as defined in
              ISO 216
           'iso-b4': Specifies the ISO B4 size: 250 mm by 353 mm as defined in
              ISO 216
           'iso-b5': Specifies the ISO B5 size: 176 mm by 250 mm as defined in
              ISO 216
           'iso-b6': Specifies the ISO B6 size: 125 mm by 176 mm as defined in
              ISO 216
           'iso-b7': Specifies the ISO B7 size: 88 mm by 125 mm as defined in
              ISO 216
           'iso-b8': Specifies the ISO B8 size: 62 mm by 88 mm as defined in
              ISO 216
           'iso-b9': Specifies the ISO B9 size: 44 mm by 62 mm as defined in
              ISO 216
           'iso-b10': Specifies the ISO B10 size: 31 mm by 44 mm as defined in
              ISO 216
           'na-letter': Specifies the North American letter size: 8.5 inches
              by 11 inches
           'na-legal': Specifies the North American legal size: 8.5 inches by
              14 inches
           'executive': Specifies the executive size (7.25 X 10.5 in)
           'folio': Specifies the folio size (8.5 X 13 in)
           'invoice': Specifies the invoice size (5.5 X 8.5 in)
           'ledger': Specifies the ledger size (11 X 17 in)
           'quarto': Specifies the quarto size (8.5 X 10.83 in)
           'iso-c3': Specifies the ISO C3 size: 324 mm by 458 mm as defined in
              ISO 269
           'iso-c4': Specifies the ISO C4 size: 229 mm by 324 mm as defined in
              ISO 269
           'iso-c5': Specifies the ISO C5 size: 162 mm by 229 mm as defined in
              ISO 269
           'iso-c6': Specifies the ISO C6 size: 114 mm by 162 mm as defined in
              ISO 269
           'iso-designated-long': Specifies the ISO Designated Long size: 110
              mm by 220 mm as defined in ISO 269
           'na-10x13-envelope': Specifies the North American 10x13 size: 10
              inches by 13 inches
           'na-9x12-envelope': Specifies the North American 9x12 size: 9
              inches by 12 inches
           'na-number-10-envelope': Specifies the North American number 10
              business envelope size: 4.125 inches by 9.5 inches
           'na-7x9-envelope': Specifies the North American 7x9 inch envelope
              size
           'na-9x11-envelope': Specifies the North American 9x11 inch envelope
              size
         
         
         
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           'na-10x14-envelope': Specifies the North American 10x14 inch
              envelope size
           'na-number-9-envelope': Specifies the North American number 9
              business envelope size
           'na-6x9-envelope': Specifies the North American 6x9 envelope size
           'na-10x15-envelope': Specifies the North American 10x15 envelope
              size
           'monarch-envelope': Specifies the Monarch envelope size (3.87 x 7.5
              in)
           'jis-b0': Specifies the JIS B0 size: 1030mm x 1456mm
           'jis-b1': Specifies the JIS B1 size: 728mm x 1030mm
           'jis-b2': Specifies the JIS B2 size: 515mm x 728mm
           'jis-b3': Specifies the JIS B3 size: 364mm x 515mm
           'jis-b4': Specifies the JIS B4 size: 257mm x 364mm
           'jis-b5': Specifies the JIS B5 size: 182mm x 257mm
           'jis-b6': Specifies the JIS B6 size: 128mm x 182mm
           'jis-b7': Specifies the JIS B7 size: 91mm x 128mm
           'jis-b8': Specifies the JIS B8 size: 64mm x 91mm
           'jis-b9': Specifies the JIS B9 size: 45mm x 64mm
           'jis-b10': Specifies the JIS B10 size: 32mm x 45mm
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
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