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Network Working Group                                            S. LeggRequest for Comments: 4913                                       eB2BcomCategory: Experimental                                         July 2007Abstract Syntax Notation X (ASN.X) Representationof Encoding Instructions forthe Generic String Encoding Rules (GSER)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   Abstract Syntax Notation X (ASN.X) is an Extensible Markup Language   (XML) representation for Abstract Syntax Notation One (ASN.1)   specifications.  This document specifies the ASN.X representation of   encoding instructions for the Generic String Encoding Rules (GSER).Table of Contents1. Introduction ....................................................22. Conventions .....................................................23. EncodingInstructionAssignmentList Translation ...................34. EncodingInstruction Translation .................................34.1. ChoiceOfStringsInstruction Translation .....................35. Security Considerations .........................................46. Normative References ............................................4Appendix A. ASN.1 for GSER Encoding Instruction Notation ...........6Appendix B. ASN.X for GSER Encoding Instruction Notation ...........7Legg                          Experimental                      [Page 1]

RFC 4913           ASN.X: GSER Encoding Instructions   July 20071.  Introduction   Abstract Syntax Notation X (ASN.X) [ASN.X] is an Extensible Markup   Language (XML) [XML10][XML11] representation for Abstract Syntax   Notation One (ASN.1) [X.680] specifications.  The ASN.X   representation for the ASN.1 basic notation [X.680] [X.680-1] is   described elsewhere [ASN.X].   The grammar of ASN.1 permits the application of encoding instructions   [X.680-1], through type prefixes and encoding control sections, that   modify how abstract values are encoded by nominated encoding rules.   The generic notation for type prefixes and encoding control sections   is defined by the ASN.1 basic notation; however, the notation for   specific encoding instructions, i.e., the EncodingInstruction and   EncodingInstructionAssignmentList productions of the notation, are   defined separately for each set of encoding rules using encoding   instructions.  This document specifies the ASN.X representation for   EncodingInstructionAssignmentList and EncodingInstruction as they are   defined for the Generic String Encoding Rules (GSER) [GSER][GSEREI].   ASN.X is defined in terms of rules for translating from an ASN.1   specification.  This does not preclude an ASN.X module being written   directly without a pre-existing ASN.1 module; however, such an ASN.X   module is considered valid if and only if there exists, in principle,   an ASN.1 module that when translated would yield the ASN.X module.   By design, an ASN.X module is also the Robust XML Encoding Rules   (RXER) [RXER] encoding of an ASN.1 value.  The ASN.1 type definitions   for such values, insofar as they pertain to the ASN.1 basic notation,   are provided elsewhere [ASN.X]; however, this document provides the   ASN.1 type definitions for representing GSER encoding instructions as   abstract values.  These definitions appear inAppendix A.   The ASN.X translation of the ASN.1 module inAppendix A is presented   inAppendix B.   The General Considerations of the specification for ASN.X [ASN.X]   also apply here.2.  Conventions   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document are   to be interpreted as described inBCP 14,RFC 2119 [BCP14].  The key   word "OPTIONAL" is exclusively used with its ASN.1 meaning.Legg                          Experimental                      [Page 2]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007   A reference to an ASN.1 production [X.680] (e.g., Type, NamedType) is   a reference to the text in an ASN.1 specification corresponding to   that production.   The description of the translation of GSER encoding instructions into   ASN.X makes use of definitions from the XML Information Set (Infoset)   [INFOSET].  In particular, information item property names follow the   Infoset convention of being shown in square brackets, e.g.,   [local name].  Literal values of Infoset properties are enclosed in   double quotes; however, the double quotes are not part of the   property values.  In the sections that follow, "information item"   will be abbreviated to "item", e.g., "element information item" is   abbreviated to "element item".  Element items will be referred to by   their [local name] in angle brackets, e.g., "the <type> element item"   means the element item with the [local name] "type".3.  EncodingInstructionAssignmentList Translation   As described in the specification for ASN.X [ASN.X], the translation   of an EncodingControlSection for GSER is an element item with the   [local name] "GSER".  The translation of the   EncodingInstructionAssignmentList in such an EncodingControlSection   determines the content of the <GSER> element item.   The EncodingInstructionAssignmentList for GSER is currently defined   to be empty [GSEREI]; therefore, the [attributes] and [children] of   the <GSER> element item are both empty.4.  EncodingInstruction Translation   The translation of an EncodingInstruction for GSER can appear in the   translation of an EncodingPrefix.  The translation for an   EncodingPrefix is described by the specification for ASN.X.   The translation of an EncodingInstruction for GSER is the translation   of the ChoiceOfStringsInstruction in the EncodingInstruction   (currently the only defined encoding instruction for GSER).4.1.  ChoiceOfStringsInstruction Translation   The translation of a ChoiceOfStringsInstruction is an element item   with the [local name] "choiceOfStrings".   If the ChoiceOfStringsInstruction has an AlternativesPrecedence, then   an attribute item with the [local name] "precedence" SHALL be added   to the [attributes] of the <choiceOfStrings> element item.  The   [normalized value] of this attribute item is the white space   separated list of qualified names for the expanded names [XMLNS10] ofLegg                          Experimental                      [Page 3]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007   the NamedType instances (see [RXEREI]) corresponding to the   identifiers nested in the PrecedenceList in the   AlternativesPrecedence.   Example      [GSER:CHOICE-OF-STRINGS PRECEDENCE utf8 visible] CHOICE {          visible  [RXER:NAME "ascii"] VisibleString,          utf8     UTF8String      }      <type xmlns:asnx="urn:ietf:params:xml:ns:asnx">       <prefixed>        <GSER><choiceOfStrings precedence="utf8 ascii"/></GSER>        <type>         <choice>          <element name="ascii" identifier="visible"                   type="asnx:VisibleString"/>          <element name="utf8" type="asnx:UTF8String"/>         </choice>        </type>       </prefixed>      </type>5.  Security Considerations   The ASN.X translation of a GSER encoding instruction is semantically   equivalent to the original GSER encoding instruction.  The security   considerations that apply to an application built from an original   ASN.1 specification with GSER encoding instructions apply equally to   an application built from the ASN.X translation of the ASN.1   specification.   See the main specification for ASN.X [ASN.X] for security   considerations related to ASN.X modules.6.  Normative References   [BCP14]    Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [GSER]     Legg, S., "Generic String Encoding Rules (GSER) for ASN.1              Types",RFC 3641, October 2003.   [GSEREI]   Legg, S., "Encoding Instructions for the Generic String              Encoding Rules (GSER)",RFC 4792, January 2007.Legg                          Experimental                      [Page 4]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007   [RXER]     Legg, S. and D. Prager, "Robust XML Encoding Rules (RXER)              for Abstract Syntax Notation One (ASN.1)",RFC 4910, July              2007.   [RXEREI]   Legg, S., "Encoding Instructions for the Robust XML              Encoding Rules (RXER)",RFC 4911, July 2007.   [ASN.X]    Legg, S., "Abstract Syntax Notation X (ASN.X)",RFC 4912,              July 2007.   [X.680]    ITU-T Recommendation X.680 (07/02) | ISO/IEC 8824-1,              Information technology - Abstract Syntax Notation One              (ASN.1):  Specification of basic notation.   [X.680-1]  ITU-T Recommendation X.680 (2002) Amendment 1 (10/03) |              ISO/IEC 8824-1:2002/Amd 1:2004, Support for EXTENDED-XER.   [XML10]    Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E. and              F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fourth              Edition)", W3C Recommendation,http://www.w3.org/TR/2006/REC-xml-20060816, August 2006.   [XML11]    Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E.,              Yergeau, F., and J. Cowan, "Extensible Markup Language              (XML) 1.1 (Second Edition)", W3C Recommendation,http://www.w3.org/TR/2006/REC-xml11-20060816, August 2006.   [XMLNS10]  Bray, T., Hollander, D., Layman, A., and R. Tobin,              "Namespaces in XML 1.0 (Second Edition)", W3C              Recommendation,http://www.w3.org/TR/2006/REC-xml-names-20060816, August              2006.   [INFOSET]  Cowan, J. and R. Tobin, "XML Information Set (Second              Edition)", W3C Recommendation,http://www.w3.org/TR/2004/REC-xml-infoset-20040204,              February 2004.Legg                          Experimental                      [Page 5]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007Appendix A.  ASN.1 for GSER Encoding Instruction Notation   This appendix is normative.   GSER-EncodingInstructionNotation       { iso(1) identified-organization(3) dod(6)         internet(1) private(4) enterprise(1)         xmled(21472) asnx(1) module(0) gser-ei-notation(2) }   -- Copyright (C) The IETF Trust (2007).  This version of   -- this ASN.1 module is part ofRFC 4913; see the RFC itself   -- for full legal notices.   --   -- Regarding this ASN.1 module or any portion of it, the author   -- makes no guarantees and is not responsible for any damage   -- resulting from its use.  The author grants irrevocable permission   -- to anyone to use, modify, and distribute it in any way that does   -- not diminish the rights of anyone else to use, modify, and   -- distribute it, provided that redistributed derivative works do   -- not contain misleading author or version information.   -- Derivative works need not be licensed under similar terms.   DEFINITIONS   RXER INSTRUCTIONS   AUTOMATIC TAGS   EXTENSIBILITY IMPLIED ::= BEGIN   IMPORTS       PrecedenceList           FROM AbstractSyntaxNotation-X               { iso(1) identified-organization(3) dod(6)                 internet(1) private(4) enterprise(1)                 xmled(21472) asnx(1) module(0) notation(1) }       ;   GSER-EncodingInstruction ::= [SINGULAR-INSERTIONS] CHOICE {       choiceOfStrings  GSER-ChoiceOfStringsInstruction   }   GSER-EncodingInstructionAssignmentList ::= SEQUENCE { }   GSER-ChoiceOfStringsInstruction ::= SEQUENCE {       precedence  [ATTRIBUTE] PrecedenceList OPTIONAL   }   ENCODING-CONTROL RXER       SCHEMA-IDENTITY  "urn:oid:1.3.6.1.4.1.21472.1.0.2"Legg                          Experimental                      [Page 6]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007       TARGET-NAMESPACE "urn:ietf:params:xml:ns:asnx" PREFIX "asnx"   ENDAppendix B.  ASN.X for GSER Encoding Instruction Notation   This appendix is non-normative.   <?xml version="1.0"?>   <asnx:module xmlns:asnx="urn:ietf:params:xml:ns:asnx"                name="GSER-EncodingInstructionNotation"                identifier="1.3.6.1.4.1.21472.1.0.2"                schemaIdentity="urn:oid:1.3.6.1.4.1.21472.1.0.2"                targetNamespace="urn:ietf:params:xml:ns:asnx"                targetPrefix="asnx"                extensibilityImplied="true">    <annotation>     Copyright (C) The IETF Trust (2007).  This version of     this ASN.X module is part ofRFC 4913; see the RFC itself     for full legal notices.     Regarding this ASN.X module or any portion of it, the author     makes no guarantees and is not responsible for any damage     resulting from its use.  The author grants irrevocable permission     to anyone to use, modify, and distribute it in any way that does     not diminish the rights of anyone else to use, modify, and     distribute it, provided that redistributed derivative works do     not contain misleading author or version information.     Derivative works need not be licensed under similar terms.    </annotation>    <import name="AbstractSyntaxNotation-X"            identifier="1.3.6.1.4.1.21472.1.0.1"            schemaIdentity="urn:oid:1.3.6.1.4.1.21472.1.0.1"            namespace="urn:ietf:params:xml:ns:asnx"/>    <namedType name="GSER-EncodingInstruction">     <type>      <choice insertions="singular">       <element name="choiceOfStrings"                type="asnx:GSER-ChoiceOfStringsInstruction"/>      </choice>     </type>    </namedType>    <namedType name="GSER-EncodingInstructionAssignmentList">     <type>Legg                          Experimental                      [Page 7]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007      <sequence/>     </type>    </namedType>    <namedType name="GSER-ChoiceOfStringsInstruction">     <type>      <sequence>       <optional>        <attribute name="precedence" type="asnx:PrecedenceList"/>       </optional>      </sequence>     </type>    </namedType>   </asnx:module>Author's Address   Dr. Steven Legg   eB2Bcom   Suite 3, Woodhouse Corporate Centre   935 Station Street   Box Hill North, Victoria 3129   AUSTRALIA   Phone: +61 3 9896 7830   Fax:   +61 3 9896 7801   EMail: steven.legg@eb2bcom.comLegg                          Experimental                      [Page 8]

RFC 4913           ASN.X: GSER Encoding Instructions   July 2007Full Copyright Statement   Copyright (C) The IETF Trust (2007).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Legg                          Experimental                      [Page 9]