RFC 2158 PROPOSED STANDARD EMAIL · X.400 · IMAGES

X.400 Image Body Parts

Defines how JPEG and GIF images are carried through X.400 mail and mapped to their MIME types.

On rfc-editor.org ↗
PUBLISHED
January 1998
AUTHORS
H. Alvestrand
STREAM
IETF
JPEG BODY PART OID
{ mixer-bp-data 3 }
GIF BODY PART OID
{ mixer-bp-data 4 }
PARAMETERS
None
CONVERSION
None
DOI
10.17487/RFC2158

RFC text

Contents
Original text · RFC Editor View on rfc-editor.org ↗
Network Working Group                                    H. Alvestrand
Request for Comments: 2158                                     UNINETT
Category: Standards Track                                 January 1998


                         X.400 Image Body Parts

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.

1.  Introduction

   This document contains the body parts defined in RFC 1495 for
   carrying image formats that were originally defined in MIME through
   an X.400 system.

   It also documents the OIDs assigned to these data formats as FTAM
   body parts, which allow the MIME types to be converted to FTAM body
   parts; this will probably be more useful than the new body parts
   defined here.

2.  Newly defined X.400 body parts

2.1.  The JPEG body part

   The following Extended Body Part is defined for JPEG data streams.
   It has no parameters.

       jpeg-body-part EXTENDED-BODY-PART-TYPE
         DATA            OCTET STRING
         ::= mime-jpeg-body

       mime-jpeg-body OBJECT IDENTIFIER ::=
               { mixer-bp-data 3 }

   The content is as defined in [MIME].

2.2.  The GIF body part

   The following Extended Body Part is defined for GIF data streams.  It
   has no parameters.

       gif-body-part EXTENDED-BODY-PART-TYPE
         DATA            OCTET STRING
         ::= mime-gif-body

       mime-gif-body OBJECT IDENTIFIER ::=
               { mixer-bp-data 4 }

   The content is as defined in [MIME].

3.  Defined equivalences with MIME types

3.1.  image/jpeg - jpeg-body-part

   X.400 Body Part: Extended Body Part, OID jpeg-body-part
   MIME Content-Type: image/jpeg
   Conversion: None

3.2.  image/jpeg - FTAM EMA JPEG

   X.400 Body Part: FTAM EMA JPEG
   MIME Content-Type: image/jpeg
   Conversion: None

   The OID assigned to JPEG by EMA in [MAWG] is

   { ema objects(2) messaging (2) attachments(1) jpeg-image(6) }

   while EMA's OID is

   { joint-iso-ccitt(2) country(16) us(840) organization(1)
   ema(113694) }

   making the total OID, numeric only

   { 2 16 840 1 113694 2 2 1 6 }

3.3.  image/gif - gif-body-part

   X.400 Body Part: Extended Body Part, OID gif-body-part
   MIME Content-Type: image/gif
   Conversion: None

3.4.  image/gif - FTAM EMA GIF

   X.400 Body Part: FTAM EMA GIF
   MIME Content-Type: image/jpeg
   Conversion: None

   The OID assigned to JPEG by EMA in [MAWG] is

   { ema objects(2) messaging (2) attachments(1) gif-image(4) }

4.  Security Considerations

   Security issues are not considered in this memo.

5.  References

   [MIME]
       Freed, N., and N. Borenstein, "Multipurpose Internet Mail
       Extensions (MIME) Part One: Format of Internet Message Bodies",
       RFC 2045, November 1996.

   [MAWG]
       Electronic Messaging Association Message Attachment Working Group
       (MAWG): File Transfer Body Part Feasibility Project Guide -
       version 1.5.1 - March 1996.

6.  Author's Address

   Harald Tveit Alvestrand
   UNINETT
   Postboks 6883 Elgeseter
   N-7002 TRONDHEIM

   Phone: +47 73 59 70 94
   EMail: Harald.T.Alvestrand@uninett.no

7.  Full Copyright Statement

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

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS 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.

AI ELI5

On this page
PROBLEMJPEG and GIF image formats were defined in MIME, but X.400 mail systems needed matching body parts to carry them.
MECHANISMThe RFC defines a JPEG and a GIF Extended Body Part, each a plain octet string with an object identifier, and lists how they map to the MIME types image/jpeg and image/gif with no conversion.
WHY IT MATTERSImages can pass between MIME and X.400 unchanged. The RFC also records the FTAM object identifiers for the same formats, which it expects to be more useful.

§1Purpose

This document carries the body parts defined in RFC 1495 for image formats that were originally defined in MIME through an X.400 system.

It also documents the object identifiers (OIDs) assigned to these formats as FTAM body parts, so the MIME types can be converted to FTAM body parts. The RFC says this will probably be more useful than the new body parts it defines.

Two mail systems speak different languages. This note gives picture files a name tag in the older one.

§2The JPEG and GIF Body Parts

Two new Extended Body Parts are defined, jpeg-body-part and gif-body-part. Both have no parameters, and their data is an OCTET STRING whose content is as defined in MIME.

Each is identified by an object identifier under mixer-bp-data: JPEG is { mixer-bp-data 3 } and GIF is { mixer-bp-data 4 }.

Each picture type gets its own numbered label, and the picture bytes go inside untouched.

§3Equivalences with MIME Types

Four equivalences are listed, all with conversion type "None". The image/jpeg type maps to the JPEG Extended Body Part and to the FTAM EMA JPEG body part. The image/gif type maps to the GIF Extended Body Part and to the FTAM EMA GIF body part.

The EMA JPEG OID is built from the EMA organization identifier and works out to the numeric form { 2 16 840 1 113694 2 2 1 6 }. The EMA GIF OID ends in gif-image(4) under the same EMA prefix.

A table says which old-system label matches which new-system label. Because the picture bytes are the same, nothing has to be changed on the way across.

X.400 TO MIME EQUIVALENCES (RFC 2158)
MIME typeX.400 body partConversion
image/jpegExtended Body Part, jpeg-body-partNone
image/jpegFTAM EMA JPEGNone
image/gifExtended Body Part, gif-body-partNone
image/gifFTAM EMA GIFNone

§4Security

The RFC says only that security issues are not considered in this memo. It adds no security mechanism of its own.

The note does not say anything about keeping pictures secret or safe.

§5References

[MIME]RFC 2045Freed, N., and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996.November 1996
[MAWG]Electronic Messaging Association Message Attachment Working Group (MAWG): File Transfer Body Part Feasibility Project Guide - version 1.5.1 - March 1996.