📄 rfc2049.txt
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RFC 2049 MIME Conformance November 19968. Acknowledgements This document is the result of the collective effort of a large number of people, at several IETF meetings, on the IETF-SMTP and IETF-822 mailing lists, and elsewhere. Although any enumeration seems doomed to suffer from egregious omissions, the following are among the many contributors to this effort: Harald Tveit Alvestrand Marc Andreessen Randall Atkinson Bob Braden Philippe Brandon Brian Capouch Kevin Carosso Uhhyung Choi Peter Clitherow Dave Collier-Brown Cristian Constantinof John Coonrod Mark Crispin Dave Crocker Stephen Crocker Terry Crowley Walt Daniels Jim Davis Frank Dawson Axel Deininger Hitoshi Doi Kevin Donnelly Steve Dorner Keith Edwards Chris Eich Dana S. Emery Johnny Eriksson Craig Everhart Patrik Faltstrom Erik E. Fair Roger Fajman Alain Fontaine Martin Forssen James M. Galvin Stephen Gildea Philip Gladstone Thomas Gordon Keld Simonsen Terry Gray Phill Gross James Hamilton David Herron Mark Horton Bruce Howard Bill Janssen Olle Jarnefors Risto Kankkunen Phil Karn Alan Katz Tim Kehres Neil Katin Steve Kille Kyuho Kim Anders Klemets John Klensin Valdis Kletniek Jim Knowles Stev Knowles Bob Kummerfeld Pekka Kytolaakso Stellan Lagerstrom Vincent Lau Timo Lehtinen Donald Lindsay Warner Losh Carlyn Lowery Laurence Lundblade Charles Lynn John R. MacMillan Larry Masinter Rick McGowan Michael J. McInerny Leo Mclaughlin Goli Montaser-Kohsari Tom Moore John Gardiner Myers Erik Naggum Mark Needleman Chris Newman John NoerenbergFreed & Borenstein Standards Track [Page 13]RFC 2049 MIME Conformance November 1996 Mats Ohrman Julian Onions Michael Patton David J. Pepper Erik van der Poel Blake C. Ramsdell Christer Romson Luc Rooijakkers Marshall T. Rose Jonathan Rosenberg Guido van Rossum Jan Rynning Harri Salminen Michael Sanderson Yutaka Sato Markku Savela Richard Alan Schafer Masahiro Sekiguchi Mark Sherman Bob Smart Peter Speck Henry Spencer Einar Stefferud Michael Stein Klaus Steinberger Peter Svanberg James Thompson Steve Uhler Stuart Vance Peter Vanderbilt Greg Vaudreuil Ed Vielmetti Larry W. Virden Ryan Waldron Rhys Weatherly Jay Weber Dave Wecker Wally Wedel Sven-Ove Westberg Brian Wideen John Wobus Glenn Wright Rayan Zachariassen David Zimmerman The authors apologize for any omissions from this list, which are certainly unintentional.Freed & Borenstein Standards Track [Page 14]RFC 2049 MIME Conformance November 1996Appendix A -- A Complex Multipart Example What follows is the outline of a complex multipart message. This message contains five parts that are to be displayed serially: two introductory plain text objects, an embedded multipart message, a text/enriched object, and a closing encapsulated text message in a non-ASCII character set. The embedded multipart message itself contains two objects to be displayed in parallel, a picture and an audio fragment. MIME-Version: 1.0 From: Nathaniel Borenstein <nsb@nsb.fv.com> To: Ned Freed <ned@innosoft.com> Date: Fri, 07 Oct 1994 16:15:05 -0700 (PDT) Subject: A multipart example Content-Type: multipart/mixed; boundary=unique-boundary-1 This is the preamble area of a multipart message. Mail readers that understand multipart format should ignore this preamble. If you are reading this text, you might want to consider changing to a mail reader that understands how to properly display multipart messages. --unique-boundary-1 ... Some text appears here ... [Note that the blank between the boundary and the start of the text in this part means no header fields were given and this is text in the US-ASCII character set. It could have been done with explicit typing as in the next part.] --unique-boundary-1 Content-type: text/plain; charset=US-ASCII This could have been part of the previous part, but illustrates explicit versus implicit typing of body parts. --unique-boundary-1 Content-Type: multipart/parallel; boundary=unique-boundary-2 --unique-boundary-2 Content-Type: audio/basicFreed & Borenstein Standards Track [Page 15]RFC 2049 MIME Conformance November 1996 Content-Transfer-Encoding: base64 ... base64-encoded 8000 Hz single-channel mu-law-format audio data goes here ... --unique-boundary-2 Content-Type: image/jpeg Content-Transfer-Encoding: base64 ... base64-encoded image data goes here ... --unique-boundary-2-- --unique-boundary-1 Content-type: text/enriched This is <bold><italic>enriched.</italic></bold> <smaller>as defined in RFC 1896</smaller> Isn't it <bigger><bigger>cool?</bigger></bigger> --unique-boundary-1 Content-Type: message/rfc822 From: (mailbox in US-ASCII) To: (address in US-ASCII) Subject: (subject in US-ASCII) Content-Type: Text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: Quoted-printable ... Additional text in ISO-8859-1 goes here ... --unique-boundary-1--Appendix B -- Changes from RFC 1521, 1522, and 1590 These documents are a revision of RFC 1521, 1522, and 1590. For the convenience of those familiar with the earlier documents, the changes from those documents are summarized in this appendix. For further history, note that Appendix H in RFC 1521 specified how that document differed from its predecessor, RFC 1341. (1) This document has been completely reformatted and split into multiple documents. This was done to improve the quality of the plain text version of this document, which is required to be the reference copy.Freed & Borenstein Standards Track [Page 16]RFC 2049 MIME Conformance November 1996 (2) BNF describing the overall structure of MIME object headers has been added. This is a documentation change only -- the underlying syntax has not changed in any way. (3) The specific BNF for the seven media types in MIME has been removed. This BNF was incorrect, incomplete, amd inconsistent with the type-indendependent BNF. And since the type-independent BNF already fully specifies the syntax of the various MIME headers, the type- specific BNF was, in the final analysis, completely unnecessary and caused more problems than it solved. (4) The more specific "US-ASCII" character set name has replaced the use of the informal term ASCII in many parts of these documents. (5) The informal concept of a primary subtype has been removed. (6) The term "object" was being used inconsistently. The definition of this term has been clarified, along with the related terms "body", "body part", and "entity", and usage has been corrected where appropriate. (7) The BNF for the multipart media type has been rearranged to make it clear that the CRLF preceeding the boundary marker is actually part of the marker itself rather than the preceeding body part. (8) The prose and BNF describing the multipart media type have been changed to make it clear that the body parts within a multipart object MUST NOT contain any lines beginning with the boundary parameter string. (9) In the rules on reassembling "message/partial" MIME entities, "Subject" is added to the list of headers to take from the inner message, and the example is modified to clarify this point. (10) "Message/partial" fragmenters are restricted to splitting MIME objects only at line boundaries. (11) In the discussion of the application/postscript type, an additional paragraph has been added warning about possible interoperability problems caused by embedding of binary data inside a PostScript MIME entity.Freed & Borenstein Standards Track [Page 17]RFC 2049 MIME Conformance November 1996 (12) Added a clarifying note to the basic syntax rules for the Content-Type header field to make it clear that the following two forms: Content-type: text/plain; charset=us-ascii (comment) Content-type: text/plain; charset="us-ascii" are completely equivalent. (13) The following sentence has been removed from the discussion of the MIME-Version header: "However, conformant software is encouraged to check the version number and at least warn the user if an unrecognized MIME-version is encountered." (14) A typo was fixed that said "application/external-body" instead of "message/external-body". (15) The definition of a character set has been reorganized to make the requirements clearer. (16) The definition of the "image/gif" media type has been moved to a separate document. This change was made because of potential conflicts with IETF rules governing the standardization of patented technology. (17) The definitions of "7bit" and "8bit" have been tightened so that use of bare CR, LF can only be used as end-of-line sequences. The document also no longer requires that NUL characters be preserved, which brings MIME into alignment with real-world implementations. (18) The definition of canonical text in MIME has been tightened so that line breaks must be represented by a CRLF sequence. CR and LF characters are not allowed outside of this usage. The definition of quoted- printable encoding has been altered accordingly. (19) The definition of the quoted-printable encoding now includes a number of suggestions for how quoted- printable encoders might best handle improperly encoded material. (20) Prose was added to clarify the use of the "7bit", "8bit", and "binary" transfer-encodings on multipart or message entities encapsulating "8bit" or "binary" data.Freed & Borenstein Standards Track [Page 18]
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