RFC 3470 (rfc3470) - Page 2 of 28


Guidelines for the Use of Extensible Markup Language (XML) within IETF Protocols



Alternative Format: Original Text Document



RFC 3470               XML within IETF Protocols            January 2003


   4.    XML Use Considerations and Recommendations . . . . . . . . .  7
         4.1   XML Syntax and Well-Formedness . . . . . . . . . . . .  7
         4.2   XML Information Set  . . . . . . . . . . . . . . . . .  7
         4.3   Syntactic Restrictions . . . . . . . . . . . . . . . .  8
         4.4   XML Declarations . . . . . . . . . . . . . . . . . . .  9
         4.5   XML Processing Instructions  . . . . . . . . . . . . .  9
         4.6   XML Comments . . . . . . . . . . . . . . . . . . . . . 10
         4.7   Validity and Extensibility . . . . . . . . . . . . . . 10
         4.8   Semantics as Well as Syntax. . . . . . . . . . . . . . 12
         4.9   Namespaces . . . . . . . . . . . . . . . . . . . . . . 12
               4.9.1 Namespaces and Attributes. . . . . . . . . . . . 13
         4.10  Element and Attribute Design Considerations. . . . . . 14
         4.11  Binary Data and Text with Control Characters . . . . . 16
         4.12  Incremental Processing . . . . . . . . . . . . . . . . 16
         4.13  Entity Declarations and Entity References  . . . . . . 16
         4.14  External References  . . . . . . . . . . . . . . . . . 17
         4.15  URI Processing . . . . . . . . . . . . . . . . . . . . 17
         4.16  White Space  . . . . . . . . . . . . . . . . . . . . . 18
         4.17  Interaction with the IANA  . . . . . . . . . . . . . . 19
   5.    Internationalization Considerations  . . . . . . . . . . . . 19
         5.1   Character Sets and Encodings . . . . . . . . . . . . . 19
         5.2   Language Declaration . . . . . . . . . . . . . . . . . 20
         5.3   Other Internationalization Considerations  . . . . . . 20
   6.    IANA Considerations  . . . . . . . . . . . . . . . . . . . . 21
   7.    Security Considerations  . . . . . . . . . . . . . . . . . . 21
   8.    Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22
   9.    Normative References . . . . . . . . . . . . . . . . . . . . 22
   10.   Informative References . . . . . . . . . . . . . . . . . . . 23
   11.   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 27
   12.   Full Copyright Statement . . . . . . . . . . . . . . . . . . 28

Conventions Used In This Document

   This document recommends, as policy, what specifications for Internet
   protocols -- and, in particular, IETF standards track protocol
   documents -- should include as normative language within them.  The
   capitalized keywords "SHOULD", "MUST", "REQUIRED", etc. are used in
   the sense of how they would be used within other documents with the
   meanings as specified in BCP 14, RFC 2119 [1].

1. Introduction and Overview

   The Extensible Markup Language (XML, [8]) is a framework for
   structuring data.  While it evolved from the Standard Generalized
   Markup Language (SGML, [30]) -- a markup language primarily focused
   on structuring documents -- XML has evolved to be a widely-used
   mechanism for representing structured data in protocol exchanges.
   See "XML in 10 points" [47] for an introduction to XML.



Hollenbeck, et al.       Best Current Practice