The Text/Plain Format Parameter
RFC 2646
Document | Type |
RFC - Proposed Standard
(August 1999; No errata)
Obsoleted by RFC 3676
Updates RFC 2046
Was draft-gellens-format (individual)
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Author | Randall Gellens | ||
Last updated | 2013-03-02 | ||
Stream | Legacy stream | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2646 (Proposed Standard) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group R. Gellens, Editor Request for Comments: 2646 Qualcomm Updates: 2046 August 1999 Category: Standards Track The Text/Plain Format Parameter 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 (1999). All Rights Reserved. Table of Contents 1. Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in this Document . . . . . . . . . . . . . 2 3. The Problem . . . . . . . . . . . . . . . . . . . . . . . . 2 3.1. Paragraph Text . . . . . . . . . . . . . . . . . . . . 3 3.2. Embarrassing Line Wrap . . . . . . . . . . . . . . . . . 3 3.3. New Media Types . . . . . . . . . . . . . . . . . . . . 4 4. The Format Parameter to the Text/Plain Media Type . . . . . 4 4.1. Generating Format=Flowed . . . . . . . . . . . . . . . 5 4.2. Interpreting Format=Flowed . . . . . . . . . . . . . . . 6 4.3. Usenet Signature Convention . . . . . . . . . . . . . . 7 4.4. Space-Stuffing . . . . . . . . . . . . . . . . . . . . . 7 4.5. Quoting . . . . . . . . . . . . . . . . . . . . . . . . 8 4.6. Digital Signatures and Encryption . . . . . . . . . . . 9 4.7. Line Analysis Table . . . . . . . . . . . . . . . . . . 10 4.8. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10 5. ABNF . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6. Failure Modes . . . . . . . . . . . . . . . . . . . . . . . 11 6.1. Trailing White Space Corruption . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . 12 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 12 9. Internationalization Considerations . . . . . . . . . . . . 12 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 12 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 12. Editor's Address . . . . . . . . . . . . . . . . . . . . . 13 13. Full Copyright Statement . . . . . . . . . . . . . . . . . . 14 Gellens Standards Track [Page 1] RFC 2646 The Text/Plain Format Parameter August 1999 1. Abstract Interoperability problems have been observed with erroneous labelling of paragraph text as Text/Plain, and with various forms of "embarrassing line wrap." (See section 3.) Attempts to deploy new media types, such as Text/Enriched [RICH] and Text/HTML [HTML] have suffered from a lack of backwards compatibility and an often hostile user reaction at the receiving end. What is required is a format which is in all significant ways Text/Plain, and therefore is quite suitable for display as Text/Plain, and yet allows the sender to express to the receiver which lines can be considered a logical paragraph, and thus flowed (wrapped and joined) as appropriate. This memo proposes a new parameter to be used with Text/Plain, and, in the presence of this parameter, the use of trailing whitespace to indicate flowed lines. This results in an encoding which appears as normal Text/Plain in older implementations, since it is in fact normal Text/Plain. 2. Conventions Used in this Document The key words "REQUIRED", "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as described in "Key words for use in RFCs to Indicate Requirement Levels" [KEYWORDS]. 3. The Problem The Text/Plain media type is the lowest common denominator of Internet email, with lines of no more than 997 characters (by convention usually no more than 80), and where the CRLF sequence represents a line break [MIME-IMT]. Text/Plain is usually displayed as preformatted text, often in a fixed font. That is, the characters start at the left margin of the display window, and advance to the right until a CRLF sequence is seen, at which point a new line is started, again at the left margin. When a line length exceeds the display window, some clients will wrap the line, while others invoke a horizontal scroll bar. Text which meets this description is defined by this memo as "fixed". Some interoperability problems have been observed with this media type: Gellens Standards Track [Page 2] RFC 2646 The Text/Plain Format Parameter August 1999 3.1. Paragraph TextShow full document text