Mapping between X.400 and RFC-822/MIME Message Bodies
RFC 2157

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Network Working Group                                      H. Alvestrand
Request for Comments: 2157                                       UNINETT
Category: Standards Track                                   January 1998

         Mapping between X.400 and RFC-822/MIME Message Bodies

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

Table of Contents

   1 Introduction ...........................................    2
   1.1 Glossary .............................................    3
   2 Basic rules for body part conversion ...................    4
   2.1 Generating the IPM Body from MIME ....................    5
   2.2 Generating the MIME Body from the IPMS.Body ..........    6
   2.3 Mapping the EMA FTBP parameters ......................    7
   2.3.1 Mapping GraphicStrings .............................    7
   2.3.2 Mapping specific parameters ........................    7
   2.3.3 Summary of FTBP elements generated .................   10
   2.4 Information that is lost when mapping ................   11
   3 Encapsulation of body parts ............................   11
   3.1 Encapsulation of MIME in X.400 .......................   12
   3.1.1 FTBP encapsulating body part .......................   12
   3.1.2 BP15 encapsulating body part .......................   13
   3.1.3 Encapsulation using IA5 (HARPOON) ..................   15
   3.1.4 Content passing using BP14 .........................   16
   3.2 Encapsulating X.400 Body Parts in MIME ...............   16
   3.3 Encapsulating FTBP body parts in MIME ................   17
   4 User control over the gateway choice ...................   18
   4.1 Conversion from MIME to X.400 ........................   18
   4.2 Conversion from X.400 to MIME ........................   20
   5 The equivalence registry ...............................   21
   5.1 What information one must give about a mapping
        .....................................................   21
   5.2 Equivalence summary for known X.400  and  MIME
       Types ................................................   22
   5.3 MIME to X.400 Table ..................................   23

Alvestrand                  Standards Track                     [Page 1]
RFC 2157                X.400/MIME Body Mapping             January 1998

   5.4 X.400 to MIME Table ..................................   23
   5.5 Use of OBJECT IDENTIFIERs and ASN.1 MACROS ...........   24
   6 Defined Equivalences ...................................   26
   6.1 IA5Text - text/plain .................................   26
   6.2 GeneralText - text/plain (ISO-8859) ..................   27
   6.3 BilaterallyDefined - application/octet-stream
       ......................................................   29
   6.4 FTBP  EMA  Unknown  Attachment   -
       application/octet-stream .............................   29
   6.5 MessageBodyPart - message/RFC822 .....................   30
   6.6 MessageBodyPart - multipart/* ........................   31
   6.7 Teletex - Text/Plain (Teletex) .......................   32
   7 Body parts where encapsulation is recommended ..........   33
   7.1 message/external-body ................................   34
   7.2 message/partial ......................................   35
   7.3 multipart/signed .....................................   35
   7.4 multipart/encrypted ..................................   36
   8 Conformance requirements ...............................   37
   9 Security Considerations ................................   38
   10 Author's Address ......................................   38
   11 Acknowledgements ......................................   38
    References ..............................................   38
    APPENDIXES ..............................................   41
    Appendix A: Escape code normalization ...................   41
    Appendix B: OID Assignments .............................   44
    Appendix  C:  Registration information for the
        Teletex character set ...............................   46
    Appendix  D:  IANA Registration form for new
    mappings ................................................   48
    Full Copyright Statement .................................  49

1.  Introduction

   This document is a companion to [MIXER], which defines the principles
   and translation of headers for interworking between MIME-based RFC-
   822 mail and X.400 mail.

   This document defines how to map body parts of X.400 messages into
   MIME entities and vice versa, including the handling of multipart
   messages and forwarded messages.