Encoding Instructions for the Robust XML Encoding Rules (RXER)
RFC 4911

Network Working Group                                            S. Legg
Request for Comments: 4911                                       eB2Bcom
Category: Experimental                                         July 2007

                     Encoding Instructions for the
                    Robust XML Encoding Rules (RXER)

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines encoding instructions that may be used in an
   Abstract Syntax Notation One (ASN.1) specification to alter how ASN.1
   values are encoded by the Robust XML Encoding Rules (RXER) and
   Canonical Robust XML Encoding Rules (CRXER), for example, to encode a
   component of an ASN.1 value as an Extensible Markup Language (XML)
   attribute rather than as a child element.  Some of these encoding
   instructions also affect how an ASN.1 specification is translated
   into an Abstract Syntax Notation X (ASN.X) specification.  Encoding
   instructions that allow an ASN.1 specification to reference
   definitions in other XML schema languages are also defined.

Legg                          Experimental                      [Page 1]
RFC 4911             Encoding Instructions for RXER            July 2007

Table of Contents

   1. Introduction ....................................................3
   2. Conventions .....................................................3
   3. Definitions .....................................................4
   4. Notation for RXER Encoding Instructions .........................4
   5. Component Encoding Instructions .................................6
   6. Reference Encoding Instructions .................................8
   7. Expanded Names of Components ...................................10
   8. The ATTRIBUTE Encoding Instruction .............................11
   9. The ATTRIBUTE-REF Encoding Instruction .........................12
   10. The COMPONENT-REF Encoding Instruction ........................13
   11. The ELEMENT-REF Encoding Instruction ..........................16
   12. The LIST Encoding Instruction .................................17
   13. The NAME Encoding Instruction .................................19
   14. The REF-AS-ELEMENT Encoding Instruction .......................19
   15. The REF-AS-TYPE Encoding Instruction ..........................20
   16. The SCHEMA-IDENTITY Encoding Instruction ......................22
   17. The SIMPLE-CONTENT Encoding Instruction .......................22
   18. The TARGET-NAMESPACE Encoding Instruction .....................23
   19. The TYPE-AS-VERSION Encoding Instruction ......................24
   20. The TYPE-REF Encoding Instruction .............................25
   21. The UNION Encoding Instruction ................................26
   22. The VALUES Encoding Instruction ...............................27
   23. Insertion Encoding Instructions ...............................29
   24. The VERSION-INDICATOR Encoding Instruction ....................32
   25. The GROUP Encoding Instruction ................................34
      25.1. Unambiguous Encodings ....................................36
           25.1.1. Grammar Construction ..............................37
           25.1.2. Unique Component Attribution ......................47
           25.1.3. Deterministic Grammars ............................52
           25.1.4. Attributes in Unknown Extensions ..................54
   26. Security Considerations .......................................56
   27. References ....................................................56
      27.1. Normative References .....................................56
      27.2. Informative References ...................................57
   Appendix A. GROUP Encoding Instruction Examples ...................58
   Appendix B. Insertion Encoding Instruction Examples ...............74
   Appendix C. Extension and Versioning Examples .....................87

Legg                          Experimental                      [Page 2]
RFC 4911             Encoding Instructions for RXER            July 2007

1.  Introduction

   This document defines encoding instructions [X.680-1] that may be
   used in an Abstract Syntax Notation One (ASN.1) [X.680] specification
   to alter how ASN.1 values are encoded by the Robust XML Encoding
   Rules (RXER) [RXER] and Canonical Robust XML Encoding Rules (CRXER)
   [RXER], for example, to encode a component of an ASN.1 value as an
   Extensible Markup Language (XML) [XML10] attribute rather than as a