1、 Reference number ISO/IEC 8825-4:2015(E) ISO/IEC 2015INTERNATIONAL STANDARD ISO/IEC 8825-4 Third edition 2015-11-15 Information technology ASN.1 encoding rules: XML Encoding Rules (XER) Technologies de linformation Rgles de codage ASN.1: Rgles de codage XML (XER) ISO/IEC 8825-4:2015(E) COPYRIGHT PRO
2、TECTED DOCUMENT ISO/IEC 2015 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission
3、. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2015
4、 All rights reservedISO/IEC 8825-4:2015(E) ISO/IEC 2015 All rights reserved iiiForeword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO
5、or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations,
6、 governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directiv
7、es, Part 2. The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the na
8、tional bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. This third edition cancels and replaces the second edition of I
9、SO/IEC 8825-4:2008 which has been technically revised. It also incorporates ISO/IEC 8825-4:2008/Cor.1:2012 and ISO/IEC 8825-4:2008/Cor.2:2014. ISO/IEC 8825-4 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 6, Telecommunications and information exchang
10、e between systems, in collaboration with ITU-T. The identical text is published as ITU-T X.693 (08/2015). International Telecommunication Union ITU-T X.693 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2015) SERIES X: DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY OSI networking and sy
11、stem aspects Abstract Syntax Notation One (ASN.1) Information technology ASN.1 encoding rules: XML Encoding Rules (XER) Recommendation ITU-T X.693 ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY PUBLIC DATA NETWORKS Services and facilities X.1X.19 Interfaces X.2
12、0X.49 Transmission, signalling and switching X.50X.89 Network aspects X.90X.149 Maintenance X.150X.179 Administrative arrangements X.180X.199 OPEN SYSTEMS INTERCONNECTION Model and notation X.200X.209 Service definitions X.210X.219 Connection-mode protocol specifications X.220X.229 Connectionless-mo
13、de protocol specifications X.230X.239 PICS proformas X.240X.259 Protocol Identification X.260X.269 Security Protocols X.270X.279 Layer Managed Objects X.280X.289 Conformance testing X.290X.299 INTERWORKING BETWEEN NETWORKS General X.300X.349 Satellite data transmission systems X.350X.369 IP-based ne
14、tworks X.370X.379 MESSAGE HANDLING SYSTEMS X.400X.499 DIRECTORY X.500X.599 OSI NETWORKING AND SYSTEM ASPECTS Networking X.600X.629 Efficiency X.630X.639 Quality of service X.640X.649 Naming, Addressing and Registration X.650X.679 Abstract Syntax Notation One (ASN.1) X.680X.699 OSI MANAGEMENT Systems
15、 management framework and architecture X.700X.709 Management communication service and protocol X.710X.719 Structure of management information X.720X.729 Management functions and ODMA functions X.730X.799 SECURITY X.800X.849 OSI APPLICATIONS Commitment, concurrency and recovery X.850X.859 Transactio
16、n processing X.860X.879 Remote operations X.880X.889 Generic applications of ASN.1 X.890X.899 OPEN DISTRIBUTED PROCESSING X.900X.999 INFORMATION AND NETWORK SECURITY X.1000X.1099 SECURE APPLICATIONS AND SERVICES X.1100X.1199 CYBERSPACE SECURITY X.1200X.1299 SECURE APPLICATIONS AND SERVICES X.1300X.1
17、399 CYBERSECURITY INFORMATION EXCHANGE X.1500X.1599 CLOUD COMPUTING SECURITY X.1600X.1699 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T X.693 (08/2015) i INTERNATIONAL STANDARD ISO/IEC 8825-4 RECOMMENDATION ITU-T X.693 Information technology ASN.1 encoding rules:
18、 XML Encoding Rules (XER) Summary Recommendation ITU-T X.693 | ISO/IEC 8825-4 specifies rules for encoding values of ASN.1 types using the Extensible Markup Language (XML). History Edition Recommendation Approval Study Group Unique ID *1.0 ITU-T X.693 2001-12-22 7 11.1002/1000/5565 1.1 ITU-T X.693 (
19、2001) Amd. 1 2003-10-29 17 11.1002/1000/7023 1.2 ITU-T X.693 (2001) Amd. 2 2006-06-13 17 11.1002/1000/8841 1.3 ITU-T X.693 (2001) Amd. 3 2007-05-29 17 11.1002/1000/9110 2.0 ITU-T X.693 2008-11-13 17 11.1002/1000/9611 2.1 ITU-T X.693 (2008) Cor. 1 2011-10-14 17 11.1002/1000/11381 2.2 ITU-T X.693 (200
20、8) Cor. 2 2014-03-01 17 11.1002/1000/12148 3.0 ITU-T X.693 2015-08-13 17 11.1002/1000/12489 *To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en.
21、ii Rec. ITU-T X.693 (08/2015) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU.
22、 ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for
23、 study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared o
24、n a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may cont
25、ain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express
26、 requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Propert
27、y Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of in
28、tellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 All
29、rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T X.693 (08/2015) iii CONTENTS Page 1 SCOPE 1 2 NORMATIVE REFERENCES . 1 2.1 IDENTICAL RECOMMENDATIONS | INTERNATIONAL STANDARDS . 1 2.2 ADDITIONAL REFERENCE
30、S 2 3 DEFINITIONS 2 3.1 ASN.1 BASIC ENCODING RULES (BER) 2 3.2 ADDITIONAL DEFINITIONS 2 4 ABBREVIATIONS . 4 5 ENCODINGS SPECIFIED BY THIS RECOMMENDATION | INTERNATIONAL STANDARD. 4 6 ENCODING INSTRUCTIONS SPECIFIED BY THIS RECOMMENDATION | INTERNATIONAL STANDARD . 5 7 CONFORMANCE 5 8 BASIC XML ENCOD
31、ING RULES 5 8.1 PRODUCTION OF A COMPLETE BASIC-XER ENCODING 5 8.2 THE XML PROLOG 6 8.3 THE XML DOCUMENT ELEMENT 6 8.4 ENCODING OF THE EXTERNAL TYPE 7 8.5 ENCODING OF THE OPEN TYPE . 7 8.6 DECODING OF TYPES WITH EXTENSION MARKERS 7 9 CANONICAL XML ENCODING RULES . 7 9.1 GENERAL RULES FOR CANONICAL XE
32、R . 7 9.2 REAL VALUES 8 9.3 BITSTRING VALUE . 8 9.4 OCTETSTRING VALUE . 8 9.5 SEQUENCE VALUE . 8 9.6 SET VALUE . 8 9.7 SET-OF VALUE . 9 9.8 OBJECT IDENTIFIER VALUE . 9 9.9 RELATIVE OBJECT IDENTIFIER VALUE 9 9.10 GENERALIZEDTIME . 9 9.11 UTCTIME . 9 9.12 OPEN TYPE VALUE . 10 9.13 THE TIME TYPE AND TH
33、E USEFUL TIME TYPES . 10 10 EXTENDED XML ENCODING RULES . 10 10.1 GENERAL 10 10.2 EXTENDED-XER CONFORMANCE . 11 10.3 STRUCTURE OF AN EXTENDED-XER ENCODING 13 11 NOTATION, CHARACTER SET AND LEXICAL ITEMS USED IN XER ENCODING INSTRUCTIONS 14 iv Rec. ITU-T X.693 (08/2015) 12 KEYWORDS 14 13 ASSIGNING AN
34、 XER ENCODING INSTRUCTION TO AN ASN.1 TYPE USING A TYPE PREFIX . 15 14 ASSIGNING AN XER ENCODING INSTRUCTION USING AN XER ENCODING CONTROL SECTION 18 14.1 THE ENCODING INSTRUCTION ASSIGNMENT LIST 18 14.2 IDENTIFICATION OF THE TARGETS FOR AN XER ENCODING INSTRUCTION USING A TARGET LIST 18 14.2.1 GENE
35、RAL RULES . 18 14.2.2 TARGET IDENTIFICATION USING AN ASN.1 TYPE REFERENCE AND IDENTIFIERS . 21 14.2.3 TARGET IDENTIFICATION USING A BUILT-IN TYPE NAME 22 14.2.4 USE OF IDENTIFIERS IN CONTEXT 23 14.2.5 USE OF IMPORTED TYPES IDENTIFICATION 24 15 MULTIPLE ASSIGNMENT OF XER ENCODING INSTRUCTIONS 24 15.1
36、 ORDER IN WHICH MULTIPLE ASSIGNMENTS ARE CONSIDERED . 24 15.2 EFFECT OF ASSIGNING A NEGATING ENCODING INSTRUCTION . 25 15.3 MULTIPLE ASSIGNMENT OF ENCODING INSTRUCTIONS WITH MULTIPLE CATEGORIES 25 15.4 MULTIPLE ASSIGNMENT OF XER ENCODING INSTRUCTIONS OF THE SAME CATEGORY . 25 15.5 PERMITTED COMBINAT
37、IONS OF FINAL ENCODING INSTRUCTIONS . 26 16 XER ENCODING INSTRUCTION SUPPORT FOR XML NAMESPACES AND QUALIFIED NAMES . 27 17 SPECIFICATION OF EXTENDED-XER ENCODINGS 28 17.1 THE XML DOCUMENT ELEMENT 29 17.2 THE “TYPENAMEORMODIFIEDTYPENAME“ PRODUCTION 29 17.3 THE “ATTRIBUTELIST“ PRODUCTION . 29 17.4 TH
38、E “EXTENDEDXMLVALUE“ PRODUCTION. 29 17.5 THE “EXTENDEDXMLCHOICEVALUE“ PRODUCTION 31 17.6 THE “EXTENDEDXMLSEQUENCEVALUE“ AND “EXTENDEDXMLSETVALUE“ PRODUCTIONS . 31 17.7 THE “EXTENDEDXMLSEQUENCEOFVALUE“ AND “EXTENDEDXMLSETOFVALUE“ PRODUCTIONS . 32 17.8 THE “MODIFIEDXMLINTEGERVALUE“ PRODUCTION . 33 17.
39、9 THE “MODIFIEDXMLREALVALUE“ PRODUCTION 34 18 THE ANY-ATTRIBUTES ENCODING INSTRUCTION . 34 18.1 GENERAL 34 18.2 RESTRICTIONS 35 18.3 EFFECT ON ENCODINGS 36 19 THE ANY-ELEMENT ENCODING INSTRUCTION 36 19.1 GENERAL 36 19.2 RESTRICTIONS 36 19.3 EFFECT ON ENCODINGS 37 20 THE ATTRIBUTE ENCODING INSTRUCTIO
40、N . 38 20.1 GENERAL 38 Rec. ITU-T X.693 (08/2015) v 20.2 RESTRICTIONS 38 20.3 EFFECT ON ENCODINGS 38 21 THE BASE64 ENCODING INSTRUCTION . 40 21.1 GENERAL 40 21.2 RESTRICTIONS 40 21.3 EFFECT ON ENCODINGS 40 22 THE DECIMAL ENCODING INSTRUCTION . 41 22.1 GENERAL 41 22.2 RESTRICTIONS 41 22.3 EFFECT ON E
41、NCODINGS 42 23 THE DEFAULT-FOR-EMPTY ENCODING INSTRUCTION . 42 23.1 GENERAL 42 23.2 RESTRICTIONS 43 23.3 EFFECT ON ENCODINGS 44 24 THE ELEMENT ENCODING INSTRUCTION 44 24.1 GENERAL 44 24.2 RESTRICTIONS 44 24.3 EFFECT ON ENCODINGS 44 25 THE EMBED-VALUES ENCODING INSTRUCTION 44 25.1 GENERAL 44 25.2 RES
42、TRICTIONS 45 25.3 EFFECT ON ENCODINGS 45 26 THE GLOBAL-DEFAULTS ENCODING INSTRUCTION . 46 26.1 GENERAL 46 26.2 RESTRICTIONS 46 26.3 EFFECT ON ENCODINGS 46 27 THE LIST ENCODING INSTRUCTION 47 27.1 GENERAL 47 27.2 RESTRICTIONS 47 27.3 EFFECT ON ENCODINGS 47 28 THE NAME ENCODING INSTRUCTION . 48 28.1 G
43、ENERAL 48 28.2 RESTRICTIONS 49 28.3 EFFECT ON ENCODINGS 49 29 THE NAMESPACE ENCODING INSTRUCTION . 50 29.1 GENERAL 50 29.2 RESTRICTIONS 50 29.3 EFFECT ON ENCODINGS 51 30 THE PI-OR-COMMENT ENCODING INSTRUCTION . 51 30.1 GENERAL 51 30.2 RESTRICTIONS 52 30.3 EFFECT ON THE ENCODINGS . 52 31 THE TEXT ENC
44、ODING INSTRUCTION . 52 vi Rec. ITU-T X.693 (08/2015) 31.1 GENERAL 52 31.2 RESTRICTIONS 53 31.3 EFFECT ON ENCODINGS 53 32 THE UNTAGGED ENCODING INSTRUCTION . 54 32.1 GENERAL 54 32.2 RESTRICTIONS 55 32.3 EFFECT ON ENCODINGS 55 33 THE USE-NIL ENCODING INSTRUCTION . 56 33.1 GENERAL 56 33.2 RESTRICTIONS
45、56 33.3 EFFECT ON ENCODINGS 57 34 THE USE-NUMBER ENCODING INSTRUCTION . 57 34.1 GENERAL 57 34.2 RESTRICTIONS 57 34.3 EFFECT ON ENCODINGS 57 35 THE USE-ORDER ENCODING INSTRUCTION . 58 35.1 GENERAL 58 35.2 RESTRICTIONS 58 35.3 EFFECT ON ENCODINGS 59 36 THE USE-QNAME ENCODING INSTRUCTION 59 36.1 GENERA
46、L 59 36.2 RESTRICTIONS 59 36.3 EFFECT ON ENCODINGS 60 37 THE USE-TYPE ENCODING INSTRUCTION 60 37.1 GENERAL 60 37.2 RESTRICTIONS 60 37.3 EFFECT ON ENCODINGS 61 38 THE USE-UNION ENCODING INSTRUCTION . 61 38.1 GENERAL 61 38.2 RESTRICTIONS 61 38.3 EFFECT ON ENCODINGS 62 39 THE WHITESPACE ENCODING INSTRU
47、CTION 63 39.1 GENERAL 63 39.2 RESTRICTIONS 63 39.3 EFFECT ON ENCODINGS 64 40 IDENTIFICATION OF THE ENCODING RULES . 64 ANNEX A EXAMPLES OF BASIC-XER AND CXER ENCODINGS 65 A.1 ASN.1 DESCRIPTION OF THE RECORD STRUCTURE . 65 A.2 ASN.1 DESCRIPTION OF A RECORD VALUE 65 A.3 BASIC XML REPRESENTATION OF THI
48、S RECORD VALUE 65 A.4 CANONICAL XML REPRESENTATION OF THIS RECORD VALUE . 66 ANNEX B PARTIAL XML CONTENT AND DETERMINISTIC ENCODINGS . 67 B.1 PARTIAL XML CONTENT 67 Rec. ITU-T X.693 (08/2015) vii B.2 RECOMMENDED RESTRICTIONS ON ENCODINGS PRODUCING PARTIAL XML ELEMENT CONTENT 67 ANNEX C EXAMPLES OF E
49、XTENDED-XER ENCODINGS USING XER ENCODING INSTRUCTIONS . 70 C.1 INTRODUCTION 70 C.2 SIMPLE EXAMPLES. 70 C.2.1 A BASE-BALL CARD 70 C.2.2 AN EMPLOYEE 71 C.3 MORE COMPLEX EXAMPLES . 71 C.3.1 USING A UNION OF TWO SIMPLE TYPES 71 C.3.2 USING A TYPE IDENTIFICATION ATTRIBUTE . 72 C.3.3 USING ENUMERATION VALUES . 72 C.3.4 USING AN EMPTY ENCODING FOR A DEFAULT VALUE . 72 C.3.5 USING EMBEDDED-VALUES FOR NOTIFICATION OF A PAYMENT DUE . 72
