URI Fragment Identifiers for the text/plain Media Type
RFC 5147

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 09

Network Working Group                                           E. Wilde
Request for Comments: 5147                                   UC Berkeley
Updates: 2046                                                  M. Duerst
Category: Standards Track                       Aoyama Gakuin University
                                                              April 2008

         URI Fragment Identifiers for the text/plain Media Type

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.

Abstract

   This memo defines URI fragment identifiers for text/plain MIME
   entities.  These fragment identifiers make it possible to refer to
   parts of a text/plain MIME entity, either identified by character
   position or range, or by line position or range.  Fragment
   identifiers may also contain information for integrity checks to make
   them more robust.

Wilde & Duerst              Standards Track                     [Page 1]
RFC 5147            text/plain Fragment Identifiers           April 2008

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  What Is text/plain?  . . . . . . . . . . . . . . . . . . .  3
     1.2.  What Is a URI Fragment Identifier? . . . . . . . . . . . .  4
     1.3.  Why text/plain Fragment Identifiers? . . . . . . . . . . .  4
     1.4.  Incremental Deployment . . . . . . . . . . . . . . . . . .  5
     1.5.  Notation Used in This Memo . . . . . . . . . . . . . . . .  5
   2.  Fragment Identification Methods  . . . . . . . . . . . . . . .  5
     2.1.  Fragment Identification Principles . . . . . . . . . . . .  6
       2.1.1.  Positions and Ranges . . . . . . . . . . . . . . . . .  6
       2.1.2.  Characters and Lines . . . . . . . . . . . . . . . . .  7
     2.2.  Combining the Principles . . . . . . . . . . . . . . . . .  7
       2.2.1.  Character Position . . . . . . . . . . . . . . . . . .  7
       2.2.2.  Character Range  . . . . . . . . . . . . . . . . . . .  8
       2.2.3.  Line Position  . . . . . . . . . . . . . . . . . . . .  8
       2.2.4.  Line Range . . . . . . . . . . . . . . . . . . . . . .  8
     2.3.  Fragment Identifier Robustness . . . . . . . . . . . . . .  8
   3.  Fragment Identification Syntax . . . . . . . . . . . . . . . .  9
     3.1.  Integrity Checks . . . . . . . . . . . . . . . . . . . . .  9
   4.  Fragment Identifier Processing . . . . . . . . . . . . . . . . 10
     4.1.  Handling of Line Endings in text/plain MIME Entities . . . 10
     4.2.  Handling of Position Values  . . . . . . . . . . . . . . . 11
     4.3.  Handling of Integrity Checks . . . . . . . . . . . . . . . 11
     4.4.  Syntax Errors in Fragment Identifiers  . . . . . . . . . . 12
   5.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 14
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 16

Wilde & Duerst              Standards Track                     [Page 2]
RFC 5147            text/plain Fragment Identifiers           April 2008

1.  Introduction

   This memo updates the text/plain media type defined in RFC 2046 [3]
   by defining URI fragment identifiers for text/plain MIME entities.
   This makes it possible to refer to parts of a text/plain MIME entity.
   Such parts can be identified by either character position or range,
   or by line position or range.  Integrity checking information can be
   added to a fragment identifier to make it more robust, enabling
   applications to detect changes of the entity.

   This section gives an introduction to the general concepts of text/
   plain MIME entities and URI fragment identifiers, and it discusses
   the need for fragment identifiers for text/plain and deployment
   issues.  Section 2 discusses the principles and methods on which this
   memo is based.  Section 3 defines the syntax, and Section 4 discusses
   processing of text/plain fragment identifiers.  Section 5 shows some
   examples.

1.1.  What Is text/plain?

   Internet Media Types (often referred to as "MIME types"), as defined
   in RFC 2045 [2] and RFC 2046 [3], are used to identify different
   types and sub-types of media.  RFC 2046 [3] and RFC 3676 [6] specify
   the text/plain media type, which is used for simple, unformatted
   text.  Quoting from RFC 2046 [3]: "Plain text does not provide for or