Network Working Group Donald Eastlake 3rd INTERNET-DRAFT Motorola Laboratories Expires: December 2004 June 2004 The Protocol versus Document Points of View in Computer Protocols --- -------- ------ -------- ------ -- ---- -- -------- --------- <draft-eastlake-proto-doc-pov-05.txt> Status of This Document By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. This draft is intended to become an Informational RFC. It's distribution is unlimited. Please send comments to the author. 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 a "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Abstract Two points of view are contrasted: the "document" point of view, where digital objects of interest are like pieces of paper written and viewed by people, and the "protocol" point of view where objects of interest are composite dynamic network messages. While each point of view has a place, adherence to a document point of view can be damaging to protocol design. By understanding both of these points of view, conflicts between them may be clarified and reduced. D. Eastlake 3rd [Page 1]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 Table of Contents Status of This Document....................................1 Abstract...................................................1 Table of Contents..........................................2 1. Introduction............................................3 2. Points of View..........................................3 2.1 The Basic Points of View...............................3 2.2 Questions of Meaning...................................4 2.2.1 Core Meaning.........................................4 2.2.2 Adjunct Meaning......................................5 2.3 Processing Models......................................5 2.3.1 Amount of Processing.................................5 2.3.2 Granularity of Processing............................6 2.3.3 Extensibility of Processing..........................6 2.4 Security and Canonicalization..........................7 2.4.1 Canonicalization.....................................7 2.4.2 Digital Authentication...............................8 2.4.3 Canonicalization and Digital Authentication..........9 2.4.4 Encryption..........................................10 2.5 Unique Internal Labels................................10 3. Examples...............................................11 4. Resolution of the Points of View.......................12 5. Conclusion.............................................13 Copyright and Disclaimer..................................14 Informative References....................................15 Author's Address..........................................17 Expiration and File Name..................................17 D. Eastlake 3rd [Page 2]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 1. Introduction This document contrasts two points of view: the "document" point of view, where digital objects of interest are like pieces of paper written and viewed by people, and the "protocol" point of view where objects of interest are composite dynamic network messages. Those accustomed to one point of view frequently have great difficulty in appreciating the other. Even after they understand the other, they almost always start by consider things from their accustomed point of view, assume that most of the universe of interest is best viewed from their perspective, and commonly slip back into thinking about things entirely from that point of view. While each point of view has a place, adherence to a document point of view can be damaging to protocol design. By understanding both of these points of view, conflicts between them may be clarified and reduced. Much of the IETF's traditional work has concerned low level binary protocol constructs. These are almost always viewed from the protocol point of view. But as higher level application constructs and syntaxes are involved in the IETF and other standards processes, difficulties can arise due to participants who have the document point of view. These two different points of view defined and explored in Section 2 below. Section 3 gives some examples. Section 4 tries to synthesize the views and give general design advice in areas which can reasonably be viewed either way. 2. Points of View The following subsections contrast the document and protocol points of view. Each viewpoint is EXAGGERATED for effect. The document point of view is indicated in paragraphs headed "DOCUM" while the protocol point of view is indicated in paragraphs headed "PROTO". 2.1 The Basic Points of View DOCUM: What is important are complete (digital) documents, analogous to pieces of paper, viewed by people. A major concern is to be able to present such documents as directly as possible to a court or other third party. Since what is presented to the person is all that is important, anything which can effect this, such as a "style sheet" [CSS], MUST be considered part of the document. Sometimes the fact that the "document" originates in a computer, D. Eastlake 3rd [Page 3]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 may travel over, be processed in, and stored in computer systems, and is viewed on a computer and that such operations may involve transcoding, enveloping, or data reconstruction, is forgotten. PROTO: What is important are bits on the wire generated and consumed by well defined computer protocol processes. No person ever sees the full message as such; it is only viewed as a whole by a geek when debugging and even then they see some translated visible form. If you actually ever have to demonstrate something about such a message in a court or to a third party, there isn't any way to avoid having coomputer experts interpret it. Sometimes the fact that pieces of such messages may end up being included in or influencing data displayed to a person is forgotten. 2.2 Questions of Meaning The document and protocol points of view have radically different concepts of the "meaning" of data. The document oriented tend to consider "meaning" to a human reader to be extremely important but this is something the protocol oriented rarely think about at all. This difference in point of view extends beyond the core meaning to the meaning of addenda to data. Both core and addenda meaning are discussed below. 2.2.1 Core Meaning DOCUM: The "meaning" of a document is a deep and interesting human question related to volition. It is probably necessary for the document to include or reference human language policy and/or warranty / disclaimer information. At an absolute minimum, some sort of semantic labeling is required. The assumed situation is always a person interpreting the whole "document" without other context. Thus it is reasonable to consult attorneys during message design, require human readable statements to be "within the four corners" of the document, etc. PROTO: The "meaning" of a protocol message should be clear and unambiguous from the protocol specification. It is frequently defined in terms of the state machines of the sender and recipient processes and may have only the most remote connection with human volition. Such processes have additional context and the message is usually only meaningful with that additional context. Adding any human readable text that is not functionally required is silly. Consulting attorneys during design is a bad idea that complicates the protocol and could tie a design effort in knots. D. Eastlake 3rd [Page 4]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 2.2.2 Adjunct Meaning Adjunct items can be added or are logically addenda to a message. DOCUM: From a document point of view, at the top level we have the equivalent of a person looking at a document. So adjunct items such as digital signatures, person's names, dates, etc., must be carefully labeled as to meaning. Thus a digital signature needs to include, in more or less human readable form, what that signature means (is the signer a witness, author, guarantor, authorizer, or what?). Similarly, a person's name needs to be accompanied by what that person's role is, such as editor, author, subject, or contributor. As another example, a date needs to be accompanied by the meaning of the date, such as date of creation, modification, distribution or other event. Given the unrestrained scope of what can be documented, with the document point of view there is a risk of trying to enumerate and standardize all possible "semantic tags" for each kind of adjunct data during in the design process. This can be a difficult, complex, and essentially infinite task (i.e., a rat hole). PROTO: From a protocol point of view, the semantics of the message and every adjunct in it are defined in the protocol specification. Thus, if there is a slot for a digital signature, person's name, a date, or whatever, the party that is to enter that data, the party or parties that are to read it, and its meaning are all pre- defined. Even if there are several possible meanings, the specific meaning that applies can be specified by a separate enumerated type field. There is no reason to have such a field be directly human readable. Only the "meanings" directly relevant to the particular protocol need be considered. Another way to look at this is that the "meaning" of each adjunct, instead of being pushed into and coupled with the adjunct itself, as the document point of view encourages, is commonly promoted to the level of the protocol specification, resulting in simpler adjuncts. 2.3 Processing Models The document oriented and protocol oriented have very different views on what is likely to happen to an object. 2.3.1 Amount of Processing DOCUM: The model is of a quasi-static object like a piece of paper. About all you do to pieces of paper is transfer them as a whole, D. Eastlake 3rd [Page 5]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 from one storage area to another, or add signatures, date stamps, or similar adjuncts. (Possibly you might want an extract from a document or to combine multiple documents into a summary but this isn't the common case.) PROTO: The standard model of a protocol message is as an ephemeral composite, multi-level object created by a source process and consumed by a destination process. Such a message is constructed from information contained in previously received messages, locally stored information, local calculations, etc. It is normal for there to be quite complex processing. 2.3.2 Granularity of Processing DOCUM: The document view is generally of uniform processing or evaluation of the object being specified. There may be an allowance for attachments or addenda but if so they would probably be simple, one level, self documenting attachments or addenda. (Separate processing of an attachment or addenda is possible but not usual.) PROTO: Processing is complex and almost always affects different pieces of the message differently. Some pieces may be intended for use only by the destination process, and may be extensively processed there. Others may be present so the destination process can, at some point, do minimal processing and forward them in other messages to yet other processes. The object's structure can be quite rich and have multilevel or recursive aspects. Because messages are processed in context, you can have things like a signature which covers the combination of some date in the message, some received in previous messages and stored, and some locally calculated data. 2.3.3 Extensibility of Processing DOCUM: The document oriented don't usually think of extensibility as a major problem. They assume that their design, perhaps with some simple version scheme, will meet all requirements. Or, coming from an SGML/DTD world of closed systems, they may assume that knowledge of new versions or extensions can be easily and synchronously distributed to all participating sites. PROTO: Those who are protocol oriented assume that protocols will always need to be extended and that it will not be possible to update all implementations as such extensions are deployed and/or retired. This is a difficult problem but those from the protocol D. Eastlake 3rd [Page 6]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 point of view try to provide the tools need. For example, they specify carefully defined versioning and extension/feature labeling, include the ability to negotiate version and features where possible and at least a specification of how parties running different levels should interact, providing length/delimiting information for all data so it can at least be skipped if not understood, and provide destination labeling so that a process can tell that it should ignore data except for passing it through to a later player. 2.4 Security and Canonicalization Security is a subtle area. Some of the problems can be solved in a general way, and those solutions are typically incorporated into standard security syntaxes such as those for ASN.1 [RFC 2630] and XML [RFC 3275. XMLENC]. But there are application specific questions, particularly questions of exactly what information for which protocols need to provide authentication or confidentiality. Questions of exactly what needs to be secured and how to do so robustly are deeply entwined with canonicalization. They are also somewhat different for authentication and encryption, as discussed below. 2.4.1 Canonicalization Canonicalization is the transformation of the "significant" information in a message into a "standard" form, discarding "insignificant" information. For example, encoding into a standard character set or changing line endings into a standard encoding and discarding the information as to what the original character set or line ending encodings were. Obvious, what is "significant" and what is "insignificant" varies with the application or protocol and can be tricky to determine. However, it is common that for each particular syntax, such as ASCII [ASCII], ASN.1 [ASN.1], or XML [XML], a standard canonicalization or canonicalizations are specified or developed through practice. This leads to the design of applications that assume one of such standard canonicalizations thus reducing the need for per-application canonicalization. (See also [RFC 3076, 3741].) DOCUM: From the document point of view, canonicalization is suspect if not outright evil. After all, if you have a piece of paper with writing on it, any modification to "standardize" its format can be an unauthorized change in the original message as created by the "author" who is always visualized as a person. From the document point of view, digital signatures are like authenticating D. Eastlake 3rd [Page 7]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 signatures or seals or time stamps on the bottom of the "piece of paper". They do not justify and should not depend on changes in the message appearing above them. Similarly, from the document point of view, encryption is just putting the "piece of paper" in a vault that only certain people can open, and does not justify any standardization or canonicalization of the message. PROTO: From the protocol point of view, canonicalization is simply a necessity. It is just a question of exactly what canonicalization or canonicalizations to apply to a pattern of bits that are calculated, processed, stored, communicated, and finally parsed and acted on. Most of these bits have never been seen and never will be seen by a person. In fact, many of the parts of the message will be artifacts of encoding, protocol structure, and computer representation rather than anything intended for a person to see. Perhaps in theory, the "original", idiosyncratic form of any digitally signed part could be conveyed unchanged through the computer process, storage, and communications channels which implement the protocol and usefully signed in that form. But in practical systems of any complexity, this is unreasonably difficult, at least for most parts of messages. And if it were possible, it would be virtually useless, because to authenticate messages you would still have to determine their equivalence with the preserved original form. Thus, signed data must be canonicalized as part of signing and verification to compensate for insignificant changes made in processing, storage, and communication. Even if, miraculously, an initial system design avoids all cases of signed message reconstruction based on processed data or re-encoding based on character set or line ending or capitalization or numeric representation or time zones or whatever, later protocol revisions and extensions are certain to eventually require such reconstruction and/or re-encoding. If such "insignificant" changes are not ameliorated by canonicalization, signatures won't work, as descussed in more detail in 2.4.3 below. 2.4.2 Digital Authentication DOCUM: The document-oriented view on authentication tends to be a "digital signature" and "forms" point of view. (The "forms" point of view is a subset of the document point of view which believes that a principle activity is presenting forms to human beings so they can fill out and sign portions of those forms [XForms].) Since the worry is always about human third parties and viewing the document in isolation, those who are document oriented always want "digital signature" (asymmetric key) authentication with its characteristics of "non-repudiability", etc. As a result, they D. Eastlake 3rd [Page 8]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 reject secret key based message autentication codes, which provide the verifier with the capability of forging an authentication code, as useless. (See any standard reference on the subject for the usual meaning of these terms.) From their point of view, you have a piece of paper or form which a person signs. Sometimes a signature covers only part of a form, but that's usually because a signature can only cover data which is already there. And normally at least one signature covers the "whole" document/form. Thus they want to be able to insert digital signatures into documents without changing the document type and even "inside" the data being signed, which requires a mechanism to skip the signature so that it does not try to sign itself. PROTO: From a protocol point of view, the right kind of authentication to use, whether "digital signature" or symmetric keyed authentication code (or biometric or whatever), is just another engineering decision affected by question of efficiency, desired security model, etc. Furthermore, the concept of signing a "whole" message seems very peculiar (unless it is a copy being saved for archival purposes in which case you might be signing a whole archive at once anyway). Typical messages are made up of various pieces with various destinations, sources, and security requirements. Furthermore, there are commonly fields you can't sign because they change as the message is communicated and processed, such as hop counts, routing history, or local forwarding tags. Certainly, different kinds of authentication are commonly mixed in one message. 2.4.3 Canonicalization and Digital Authentication For authenticating protocol system messages of practical complexity, you are faced with the choice of (1) doing "too little canonicalization" and having brittle authentication, useless due to verification failures caused by surface representation changes without significance, or (2) doing the sometimes difficult and tricky work of selecting or designing an appropriate canonicalization or canonicalizations to be used as part of authentication generation and verification, producing robust and useful authentication, or (3) doing "too much canonicalization" and having insecure authentication, useless because it still verifies even when significant changes are made in the signed data. The only useful option above is number 2. D. Eastlake 3rd [Page 9]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 2.4.4 Encryption In terms of processing, transmission, and storage, encryption turns out to be much easier than signatures to get working. Why? Because the output of encryption is essentially random bits. It is clear from the beginning that those bits need to be transferred to the destination in some absolutely clean way that does not change even one bit. Because the encrypted bits are meaningless to a human being, there is no temptation from the document oriented to try to make them more "readable". So appropriate techniques of encoding at the source, such as Base64 [RFC 2045], and decoding at the destination, are always incorporated to protect or "armor" the encrypted data. While the application of canonicalization is more obvious with digital signatures, it may also apply to encryption, particularly encryption of parts of a message. Sometimes elements of the environment where the plain text data is found may affect its interpretation. For example, interpretation can be affected by the character encoding or bindings of dummy symbols. When the data is decrypted, it may be into an environment with a different character encoding or dummy symbol bindings. With a plain text message part, it is usually clear which of these environmental elements need to be incorporated in or conveyed with the message. But an encrypted message part is opaque. Thus some canonical representation that incorporates such environmental factors may be needed. DOCUM: Encryption of the entire document is usually what is thought of. Because signatures are always thought of as human assent, people with a document point of view tend to vehemently assert that encrypted data should never be signed unless you know what the plain text of it was. PROTO: Messages are complex composite multi-level structures some pieces of which are forwarded multiple hops. Thus the design question is what fields should be encrypted by what techniques to what destination or destinations and with what canonicalization. It sometimes makes perfect sense to sign encrypted data you don't understand; for example, the signature could just be for integrity protection or as a time stamp, as specified in the protocol. 2.5 Unique Internal Labels It is desirable to be able to reference parts of structured messages or objects by some sort of "label" or "id" or "tag". The idea is that this forms a fixed "anchor" that can be used "globally", at least within an application domain, to reference the tagged part. DOCUM: From the document point of view, it seems logical to just D. Eastlake 3rd [Page 10]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 provide for a text tag. The concept would be that users or applications could easily come up with short readable tags. These would probably be meaningful to a person if humanly generated (e.g., "Susan") and at least fairly short and systematic if automatically generated (i.e., "A123"). The ID attribute type in XML [XML] appears to have been thought of this way, although it can be used in other ways. PROTO: From a protocol point of view, unique internal labels look very different than they do from a document point of view. Since this point of view assumes that pieces of different protocol messages will later be combined in a variety of ways, previously unique labels can conflict. There are really only three possibilities if you need such tags, as follows: (1) Have a system for dynamically rewriting such tags to maintain uniqueness. This is usually a disaster as it (a) invalidates any stored copies of the tags that are not rewritten, and it is usually impossible to be sure there aren't more copies lurking somewhere you failed to update, and (b) invalidates digital signatures that cover a changed tag. (2) Use some form of hierarchical qualified tags. Thus the total tag can remain unique even if a part is moved, because its qualification changes. This avoids the digital signature problems of the above possibility. But it destroys the concept of a globally-unique anchor embedded in and moving with the data. And stored tags may still be invalidated by data moves. Nevertheless, within the scope of a particular carefully designed protocol, such as IOTP [RFC 2801], this can work. (3) Construct a lengthy globally-unique tag string. This can be done successfully by using a good enough random number generator and big enough random tags (perhaps about 24 characters) or more sequentially as in the way email messages IDs are created [RFC 2822]. Thus, from a protocol point of view, such tags are difficult but if you really need them, choice 3 works best. 3. Examples IETF protocols are replete with examples of the protocol viewpoint such as TCP [RFC 793], IPSEC [RFC 2411], SMTP [RFC 2821], and IOTP [RFC 2801, 2802]. The eXtensible Markup Language [XML] is an example of something that can easily be viewed both ways and where the best results frequently result from attention to both the document and the protocol point of view. Computerized court documents, human-to-human email, and the X.509v3 D. Eastlake 3rd [Page 11]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 Certificate [X509v3], particularly the X509v3 policy portion, are examples primarily designed from the document point of view. 4. Resolution of the Points of View There is some merit to each point of view. Certainly the document point of view has some intuitive simplicity and appeal and is OK for applications where it meets their needs. The protocol point of view can come close to encompassing the document point of view as a limiting case. In particular, it does so under the following circumstances: 1. As the complexity of messages declines to a single payload (perhaps with a few attachments). 2. As the mutability of the payload declines to some standard format that needs little or no canonicalization. 3. As the number of parties and amount of processing as messages are transferred declines. 4. As the portion of the message intended for more or less direct human consumption increases. Under the above circumstances, the protocol point of view would be narrowed to something quite close to the document point of view. Even when the document point of view is questionable, the addition of a few options to a protocol will usually mollify the perceived needs of those looking at things from that point of view. For example, adding optional non-canonicalication or an optional policy statement, or inclusion of semantic labels, or the like. On the other hand, the document point of view is hard to stretch to encompass the protocol case. From a strict piece of paper perspective: canonicalization is wrong; inclusion of human language policy text within every significant object and a semantic tag with every adjunct should be mandatory; and so on. Objects designed in this way are rarely suitable for protocol use as they tend to be improperly structured to accommodate hierarchy and complexity, inefficient (due to unnecessary text and self-documenting inclusions), and insecure (due to brittle signatures). Thus, to produce usable protocols, it is best to start with the protocol point of view and add such document point of view items as are necessary to achieve consensus. D. Eastlake 3rd [Page 12]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 5. Conclusion I hope that this document will help explain to those of either point of view where those with the other view are coming from. It is my hope that this will decrease conflict, shed some light -- in particular on the difficulties of security design -- and lead to better protocol designs. D. Eastlake 3rd [Page 13]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 Copyright and Disclaimer Copyright (C) The Internet Society 2004. This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. D. Eastlake 3rd [Page 14]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 Informative References [ASCII] - "USA Standard Code for Information Interchange", X3.4, American National Standards Institute: New York, 1968. [ASN.1] - ITU-T Recommendation X.680 (1997) | ISO/IEC 8824-1:1998, "Information Technology - Abstract Syntax Notation One (ASN.1): Specification of Basic Notation". ITU-T Recommendation X.690 (1997) | ISO/IEC 8825-1:1998, "Information Technology - ASN.1 Encoding Rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)". <http://www.itu.int/ITU-T/studygroups/com17/languages/index.html>. [CSS] - "Cascading Style Sheets, level 2 revision 1 CSS 2.1 Specification", B. Bos, T. Gelik, I. Hickson, H. Lie, W3C Candidate Recommendation, 25 February 2004. <http://www.w3.org/TR/CSS21> [RFC 793] - "Transmission Control Protocol", J. Postel, Sep-01-1981. [RFC 2045] - "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", N. Freed & N. Borenstein, November 1996. [RFC 2411] - "IP Security Document Roadmap", R. Thayer, N. Doraswamy, R. Glenn, November 1998. [RFC 2630] - "Cryptographic Message Syntax", R. Housley, June 1999. [RFC 2801] - "Internet Open Trading Protocol - IOTP Version 1.0", D. Burdett, April 2000. [RFC 2802] - "Digital Signatures for the v1.0 Internet Open Trading Protocol (IOTP)", K. Davidson, Y. Kawatsura, April 2000. [RFC 2821] - "Simple Mail Transfer Protocol", J. Klensin, Editor, April 2001. [RFC 2822] - "Internet Message Format", P. Resnick, Editor, April 2001. [RFC 3076] - "Canonical XML Version 1.0", J. Boyer, March 2001. [RFC 3275] - "(Extensible Markup Language) XML-Signature Syntax and Processing", D. Eastlake, J. Reagle, D. Solo, March 2002. [RFC 3741] - "Exclusive XML Canonicalization Version 1.0", J. Boyer, D. Eastlake 3rd, J. Reagle, March 2004. D. Eastlake 3rd [Page 15]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 [X509v3] - "ITU-T Recommendation X.509 version 3 (1997), Information Technology - Open Systems Interconnection - The Directory Authentication Framework", ISO/IEC 9594-8:1997. [XForms] - "XForms 1.0", M. Dubinko, L. Klotz, R. Merrick, T. Raman, W3C Recommendation 14 October 2003. <http://www.w3.org/TR/xforms/> [XML] - "Extensible Markup Language (XML) 1.0 Recommendation (2nd Edition)". T. Bray, J. Paoli, C. M. Sperberg-McQueen, E. Maler, October 2000. <http://www.w3.org/TR/2000/REC-xml-20001006> [XMLENC] - "XML Encryption Syntax and Processing", J. Reagle, D. Eastlake, December 2002. <http://www.w3.org/TR/2001/RED-xmlenc-core- 20021210/> D. Eastlake 3rd [Page 16]
INTERNET-DRAFT Protocol versus Document Viewpoints June 2004 Author's Address The author of this document is: Donald E. Eastlake 3rd Motorola Laboratories 155 Beaver Street Milford, MA 01757 USA Phone: +1 508-786-7554 (w) +1 508-634-2066 (h) Fax: +1 508-786-7501 (w) EMail: Donald.Eastlake@motorola.com Expiration and File Name This draft expires December 2004. Its file name is <draft-eastlake-proto-doc-pov-05.txt>. D. Eastlake 3rd [Page 17]