INTERNATIONAL TELECOMMUNICATION UNION
ITU-T
X.680
TELECOMMUNICATION
STANDARDIZATION SECTOR
OF ITU
(07/2002)
SERIES X: DATA NETWORKS AND OPEN SYSTEM
COMMUNICATIONS
OSI networking and system aspects – Abstract Syntax
Notation One (ASN.1)
Information technology – Abstract Syntax
Notation One (ASN.1): Specification of basic
notation
ITU-T Recommendation X.680
ITU-T X-SERIES RECOMMENDATIONS
DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS
PUBLIC DATA NETWORKS
Services and facilities X.1–X.19
Interfaces X.20–X.49
Transmission, signalling and switching X.50–X.89
Network aspects X.90–X.149
Maintenance X.150–X.179
Administrative arrangements X.180–X.199
OPEN SYSTEMS INTERCONNECTION
Model and notation X.200–X.209
Service definitions X.210–X.219
Connection-mode protocol specifications X.220–X.229
Connectionless-mode protocol specifications X.230–X.239
PICS proformas X.240–X.259
Protocol Identification X.260–X.269
Security Protocols X.270–X.279
Layer Managed Objects X.280–X.289
Conformance testing X.290–X.299
INTERWORKING BETWEEN NETWORKS
General X.300–X.349
Satellite data transmission systems X.350–X.369
IP-based networks X.370–X.399
MESSAGE HANDLING SYSTEMS X.400–X.499
DIRECTORY X.500–X.599
OSI NETWORKING AND SYSTEM ASPECTS
Networking X.600–X.629
Efficiency X.630–X.639
Quality of service X.640–X.649
Naming, Addressing and Registration X.650–X.679
Abstract Syntax Notation One (ASN.1) X.680–X.699
OSI MANAGEMENT
Systems Management framework and architecture X.700–X.709
Management Communication Service and Protocol X.710–X.719
Structure of Management Information X.720–X.729
Management functions and ODMA functions X.730–X.799
SECURITY X.800–X.849
OSI APPLICATIONS
Commitment, Concurrency and Recovery X.850–X.859
Transaction processing X.860–X.879
Remote operations X.880–X.899
OPEN DISTRIBUTED PROCESSING X.900–X.999
For further details, please refer to the list of ITU-T Recommendations.
ITU-T Rec. X.680 (07/2002) i
INTERNATIONAL STANDARD ISO/IEC 8824-1
ITU-T RECOMMENDATION X.680
Information technology –
Abstract Syntax Notation One (ASN.1):
Specification of basic notation
Summary
This Recommendation | International Standard provides a notation called Abstract Syntax Notation One (ASN.1) for
defining the syntax of information data. It defines a number of simple data types and specifies a notation for referencing
these types and for specifying values of these types.
The ASN.1 notations can be applied whenever it is necessary to define the abstract syntax of information without
constraining in any way how the information is encoded for transmission.
Source
ITU-T Recommendation X.680 was prepared by ITU-T Study Group 17 (2001-2004) and approved on 14 July 2002. An
identical text is also published as ISO/IEC 8824-1.
FOREWORD
The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of
telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of
ITU. 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 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-T's purview, the necessary standards are
prepared on 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.
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 Property 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/had not] received notice of intellectual
property, protected by patents, which may be required to implement this Recommendation. However,
implementors are cautioned that this may not represent the latest information and are therefore strongly
urged to consult the TSB patent database.
ITU 2003
All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the
prior written permission of ITU.
ii ITU-T Rec. X.680 (07/2002)
ITU-T Rec. X.680 (07/2002) iii
11.18 Ellipsis ........................................................................................................................................... 19
CONTENTS
Page
Introduction ............................................................................................................................................................... vii
1 Scope .............................................................................................................................................................. 1
2 Normative references ..................................................................................................................................... 1
2.1 Identical Recommendations | International Standards ........................................................................ 1
2.2 Additional references .......................................................................................................................... 2
3 Definitions...................................................................................................................................................... 2
3.1 Information object specification.......................................................................................................... 2
3.2 Constraint specification....................................................................................................................... 2
3.3 Parameterization of ASN.1 specification ............................................................................................ 2
3.4 Structure for identification of organizations........................................................................................ 3
3.5 Universal Multiple-Octet Coded Character Set (UCS) ....................................................................... 3
3.6 Additional definitions.......................................................................................................................... 3
4 Abbreviations ................................................................................................................................................. 7
5 Notation.......................................................................................................................................................... 8
5.1 General................................................................................................................................................ 8
5.2 Productions.......................................................................................................................................... 8
5.3 The alternative collections .................................................................................................................. 8
5.4 Non-spacing indicator ......................................................................................................................... 9
5.5 Example of a production ..................................................................................................................... 9
5.6 Layout ................................................................................................................................................. 9
5.7 Recursion ............................................................................................................................................ 9
5.8 References to permitted sequences of lexical items ............................................................................ 9
5.9 References to a lexical item ................................................................................................................ 9
5.10 Short-hand notations ........................................................................................................................... 9
5.11 Value references and the typing of values........................................................................................... 10
6 The ASN.1 model of type extension .............................................................................................................. 10
7 Extensibility requirements on encoding rules................................................................................................. 11
8 Tags ................................................................................................................................................................ 12
9 Use of the ASN.1 notation.............................................................................................................................. 12
10 The ASN.1 character set................................................................................................................................. 13
11 ASN.1 lexical items........................................................................................................................................ 14
11.1 General rules ....................................................................................................................................... 14
11.2 Type references ................................................................................................................................... 14
11.3 Identifiers ............................................................................................................................................ 15
11.4 Value references.................................................................................................................................. 15
11.5 Module references............................................................................................................................... 15
11.6 Comments ........................................................................................................................................... 15
11.7 Empty lexical item .............................................................................................................................. 15
11.8 Numbers.............................................................................................................................................. 15
11.9 Real numbers....................................................................................................................................... 16
11.10 Binary strings ...................................................................................................................................... 16
11.11 XML binary string item ...................................................................................................................... 16
11.12 Hexadecimal strings............................................................................................................................ 16
11.13 XML hexadecimal string item............................................................................................................. 16
11.14 Character strings.................................................................................................................................. 17
11.15 XML character string item .................................................................................................................. 17
11.16 Assignment lexical item...................................................................................................................... 19
11.17 Range separator................................................................................................................................... 19
