ISO/IEC 8824-4:2015

INTERNATIONAL ISO/IEC
STANDARD 8824-4
Fifth edition
2015-11-15

Information technology — Abstract
Syntax Notation One (ASN.1):
Parameterization of ASN.1 specifications
Technologies de l'information — Notation de syntaxe abstraite numéro
un (ASN.1): Paramétrage des spécifications de la notation de syntaxe
abstraite numéro un






Reference number
ISO/IEC 8824-4:2015(E)
©
ISO/IEC 2015

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ISO/IEC 8824-4:2015(E)
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ii © ISO/IEC 2015 – All rights reserved

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ISO/IEC 8824-4:2015(E)

Foreword
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 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, 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 Directives, 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 national 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 fifth edition cancels and replaces the fourth edition of ISO/IEC 8824-4:2008 which has been technically
revised. It also incorporates ISO/IEC 8824-4:2008/Cor.1:2014.
ISO/IEC 8824-4 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 6, Telecommunications and information exchange between systems, in collaboration with
ITU-T. The identical text is published as ITU-T X.683 (08/2015).
© ISO/IEC 2015 – All rights reserved iii

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I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n


ITU-T X.683
(08/2015)
TELECOMMUNICATION
STANDARDIZATION SECTOR
OF ITU

SERIES X: DATA NETWORKS, OPEN SYSTEM
COMMUNICATIONS AND SECURITY
OSI networking and system aspects – Abstract Syntax
Notation One (ASN.1)


Information technology – Abstract Syntax
Notation One (ASN.1): Parameterization of
ASN.1 specifications

Recommendation ITU-T X.683

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ITU-T X-SERIES RECOMMENDATIONS
DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY

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.379
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.889
Generic applications of ASN.1 X.890–X.899
OPEN DISTRIBUTED PROCESSING X.900–X.999
INFORMATION AND NETWORK SECURITY X.1000–X.1099
SECURE APPLICATIONS AND SERVICES X.1100–X.1199
CYBERSPACE SECURITY X.1200–X.1299
SECURE APPLICATIONS AND SERVICES X.1300–X.1399
CYBERSECURITY INFORMATION EXCHANGE X.1500–X.1599
CLOUD COMPUTING SECURITY X.1600–X.1699

For further details, please refer to the list of ITU-T Recommendations.

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INTERNATIONAL STANDARD ISO/IEC 8824-4
RECOMMENDATION ITU-T X.683
Information technology – Abstract Syntax Notation One (ASN.1):
Parameterization of ASN.1 specifications



Summary
Recommendation ITU-T X.683 | ISO/IEC 8824-4 defines the provisions for parameterized reference names and
parameterized assignments for data types which are useful for the designer when writing specifications where some
aspects are left undefined at certain stages of the development to be filled in at a later stage to produce a complete
definition of an abstract syntax.


History
*
Edition Recommendation Approval Study Group Unique ID
1.0 ITU-T X.683 1994-07-01 7 11.1002/1000/3045
2.0 ITU-T X.683 1997-12-12 7 11.1002/1000/4446
2.1 ITU-T X.683 (1997) Amd. 1 1999-06-18 7 11.1002/1000/4703
3.0 ITU-T X.683 2002-07-14 17 11.1002/1000/6088
3.1 ITU-T X.683 (2002) Technical Cor. 1 2007-05-29 17 11.1002/1000/9107
4.0 ITU-T X.683 2008-11-13 17 11.1002/1000/9607
4.1 ITU-T X.683 (2008) Cor. 1 2014-03-01 17 11.1002/1000/12146
5.0 ITU-T X.683 2015-08-13 17 11.1002/1000/12482






*
To access the Recommendation, type the URL http://handle.itu.int/ in the address field of your web browser, followed by the
Recommendation's unique ID. For example, http://handle.itu.int/11.1002/1000/11830-en.
  Rec. ITU-T X.683 (08/2015) i

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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. 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.
Compliance with this Recommendation is voluntary. However, the Recommendation may contain 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 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 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 not received notice of intellectual 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 rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the
prior written permission of ITU.
ii Rec. ITU-T X.683 (08/2015)

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CONTENTS
Page
Introduction . iv
1 Scope . 1
2 Normative references . 1
2.1 Identical Recommendations | International Standards . 1
3 Definitions . 1
3.1 Specification of basic notation . 1
3.2 Information object specification . 1
3.3 Constraint specification . 1
3.4 Additional definitions . 1
4 Abbreviations . 2
5 Convention . 2
6 Notation . 2
6.1 Assignments . 2
6.2 Parameterized definitions . 2
6.3 Symbols . 3
7 ASN.1 lexical items . 3
8 Parameterized assignments . 3
9 Referencing parameterized definitions . 5
10 Abstract syntax parameters . 8
Annex A – Examples . 9
A.1 Example of the use of a parameterized type definition . 9
A.2 Example of use of parameterized definitions together with an information object class . 9
A.3 Example of parameterized type definition that is finite . 10
A.4 Example of a parameterized value definition . 11
A.5 Example of a parameterized value set definition . 11
A.6 Example of a parameterized class definition . 11
A.7 Example of a parameterized object set definition. 12
A.8 Example of a parameterized object set definition. 12
Annex B – Summary of the notation . 13

  Rec. ITU-T X.683 (08/2015) iii

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Introduction
Application designers need to write specifications in which certain aspects are left undefined. Those aspects will later be
defined by one or more other groups (each in its own way), to produce a fully defined specification for use in the
definition of an abstract syntax (one for each group).
In some cases, aspects of the specification (for example, bounds) may be left undefined even at the time of abstract
syntax definition, being completed by the specification of International Standardized Profiles or functional profiles from
some other body.
NOTE 1 – It is a requirement imposed by this Recommendation | International Standard that any aspect that is not solely
concerned with the application of constraints has to be completed prior to the definition of an abstract syntax.
In the extreme case, some aspects of the specification may be left for the implementer to complete, and would then be
specified as part of the Protocol Implementation Conformance Statement.
While the provisions of Rec. ITU-T X.681 | ISO/IEC 8824-2 and Rec. ITU-T X.682 | ISO/IEC 8824-3 provide a
framework for the later completion of parts of a specification, they do not of themselves solve the above requirements.
Additionally, a single designer sometimes requires to define many types, or many information object classes, or many
information object sets, or many information objects, or many values, which have the same outer level structure, but
differ in the types, or information object classes, or information object sets, or information objects, or values, that are
used at an inner level. Instead of writing out the outer level structure for every such occurrence, it is useful to be able to
write it out once, with parts left to be defined later, then to refer to it and provide the additional information.
All these requirements are met by the provision for parameterized reference names and parameterized assignments by
this Recommendation | International Standard.
The syntactic form of a parameterized reference name is the same as that of the corresponding normal reference name,
but the following additional considerations apply:
– When it is assigned in a parameterized assignment statement, it is followed by a list of dummy reference
names in braces, each possibly accompanied by a governor; these reference names have a scope which is
the right-hand side of the assignment statement, and the parameter list itself.
NOTE 2 – This is what causes it to be recognized as a parameterized reference name.
– When it is exported or imported, it is followed by a pair of empty braces to distinguish it as a
parameterized reference name.
– When it is used in any construct, it is followed by a list of syntactic constructions, one for each dummy
reference name, that provide an assignment to the dummy reference name for the purposes of that use
only.
Dummy reference names have the same syntactic form as the corresponding normal reference name, and can be used
anywhere on the right-hand side of the assignment statement that the corresponding normal reference name could be
used. All such usages are required to be consistent.

iv Rec. ITU-T X.683 (08/2015)

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ISO/IEC 8824-4 : 2005 (E)
INTERNATIONAL STANDARD
ITU-T RECOMMENDATION
Information technology –
Abstract Syntax Notation One (ASN.1):
Parameterization of ASN.1 specifications
1 Scope
This Recommendation | International Standard is part of Abstract Syntax Notation One (ASN.1) and defines notation for
parameterization of ASN.1 specifications.
2 Normative references
The following Recommendations and International Standards contain provisions which, through reference in this text,
constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated
were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this
Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent edition
of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently valid
International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently valid
ITU-T Recommendations.
2.1 Identical Recommendations | International Standards
– Recommendation ITU-T X.680 (2015) | ISO/IEC 8824-1:2015, Information technology – Abstract Syntax
Notation One (ASN.1): Specification of basic notation.
– Recommendation ITU-T X.681 (2015) | ISO/IEC 8824-2:2015, Information technology – Abstract Syntax
Notation One (ASN.1): Information object specification.
– Recommendation ITU-T X.682 (2015) | ISO/IEC 8824-3:2015, Information technology – Abstract Syntax
Notation One (ASN.1): Constraint specification.
3 Definitions
For the purposes of this Recommendation | International Standard, the following definitions apply.
3.1 Specification of basic notation
This Recommendation | International Standard uses the terms defined in Rec. ITU-T X.680 | ISO/IEC 8824-1.
3.2 Information object specification
This Recommendation | International Standard uses the terms defined in Rec. ITU-T X.681 | ISO/IEC 8824-2.
3.3 Constraint specification
This Recommendation | International Standard uses the terms defined in Rec. ITU-T X.682 | ISO/IEC 8824-3.
3.4 Additional definitions
3.4.1 normal reference name: A reference name defined, without parameters, by means of an "Assignment" other
than a "ParameterizedAssignment". Such a name references a complete definition and is not supplied with actual
parameters when used.
3.4.2 parameterized reference name: A reference name defined using a parameterized assignment, which
references an incomplete definition and which, therefore, must be supplied with actual parameters when used.
  Rec. ITU-T X.683 (08/2015) 1

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ISO/IEC 8824-4 : 2005 (E)
3.4.3 parameterized type: A type defined using a parameterized type assignment and thus whose components are
incomplete definitions which must be supplied with actual parameters when the type is used.
3.4.4 parameterized value: A value defined using a parameterized value assignment and thus whose value is
incompletely specified and must be supplied with actual parameters when used.
3.4.5 parameterized value set: A value set defined using a parameterized value set assignment and thus whose
values are incompletely specified and must be supplied with actual parameters when used.
3.4.6 parameterized object class: An information object class defined using a parameterized object class assignment
and thus whose field specifications are incompletely specified and must be supplied with actual parameters when used.
3.4.7 parameterized object: An information object defined using a parameterized object assignment and thus whose
components are incompletely specified and must be supplied with actual parameters when used.
3.4.8 parameterized object set: An information object set defined using a parameterized object set assignment and
thus whose objects are incompletely specified and must be supplied with actual parameters when used.
3.4.9 variable constraint: A constraint employed in specifying a parameterized abstract syntax, and which depends
on some parameter of the abstract syntax.
4 Abbreviations
For the purposes of this Recommendation | International Standard, the following abbreviation applies:
ASN.1 Abstract Syntax Notation One
5 Convention
This Recommendation | International Standard employs the notational convention defined in Rec. ITU-T X.680 |
ISO/IEC 8824-1, clause 5.
6 Notation
This clause summarizes the notation defined in this Recommendation | International Standard.
6.1 Assignments
The following notation which can be used as an alternative for "Assignment" (see Rec. ITU-T X.680 | ISO/IEC 8824-1,
clause 13) is defined in this Recommendation | International Standard:
– ParameterizedAssignment (see 8.1).
6.2 Parameterized definitions
6.2.1 The following notation which can be used as an alternative for "DefinedType" (see Rec. ITU-T X.680 |
ISO/IEC 8824-1, 14.1) is defined in this Recommendation | International Standard:
– ParameterizedType (see 9.2).
6.2.2 The following notation which can be used as an alternative for "DefinedValue" (see Rec. ITU-T X.680 |
ISO/IEC 8824-1, 14.1) is defined in this Recommendation | International Standard:
– ParameterizedValue (see 9.2).
6.2.3 The following notation which can be used as an alternative for "DefinedType" (see Rec. ITU-T X.680 |
ISO/IEC 8824-1, 14.1) is defined in this Recommendation | International Standard:
– ParameterizedValueSetType (see 9.2).
6.2.4 The following notation which can be used as an alternative for "ObjectClass" (see Rec. ITU-T X.681 |
ISO/IEC 8824-2, 9.2) is defined in this Recommendation | International Standard:
– ParameterizedObjectClass (see 9.2).
6.2.5 The following notation which can be used as an alternative for "Object" (see Rec. ITU-T X.681 |
ISO/IEC 8824-2, 11.3) is defined in this Recommendation | International Standard:
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ISO/IEC 8824-4 : 2005 (E)
– ParameterizedObject (see 9.2).
6.2.6 The following notation which can be used as an alternative for "ObjectSet" (see Rec. ITU-T X.681 |
ISO/IEC 8824-2, 12.3) is defined in this Recommendation | International Standard:
– ParameterizedObjectSet (see 9.2).
6.3 Symbols
The following notation which can be used as an alternative for "Symbol" (see Rec. ITU-T X.680 | ISO/IEC 8824-1, 13.1)
is defined in this Recommendation | International Standard:
– ParameterizedReference (see 9.1).
7 ASN.1 lexical items
This Recommendation | International Standard makes use of the lexical items specified in Rec. ITU-T X.680 |
ISO/IEC 8824-1, clause 12.
8 Parameterized assignments
8.1 There are parameterized assignment statements corresponding to each of the assignment statements specified in
Rec. ITU-T X.680 | ISO/IEC 8824-1 and Rec. ITU-T X.681 | ISO/IEC 8824-2. The "ParameterizedAssignment"
construct is:
ParameterizedAssignment ::=
ParameterizedTypeAssignment
| ParameterizedValueAssignment
| ParameterizedValueSetTypeAssignment
| ParameterizedObjectClassAssignment
| ParameterizedObjectAssignment
| ParameterizedObjectSetAssignment
8.2 Each "ParameterizedAssignment" has the same syntax as "Assignment" except that following the
initial lexical item there is a "ParameterList". The initial item thereby becomes a parameterized reference name
(see 3.4.2):
NOTE 1 – Rec. ITU-T X.680 | ISO/IEC 8824-1 imposes the requirement that all reference names assigned within a module,
whether parameterized or not, must be distinct.
NOTE 2 – Where value notation is governed by a parameterized type (or a type that is a parameter) the validity of value notation
within the parameterized assignment can only be determined after instantiation of the parameterized type, and may be valid for
some instantiations and invalid for others.
ParameterizedTypeAssignment ::=
typereference
ParameterList
"::="
Type
ParameterizedValueAssignment ::=
valuereference
ParameterList
Type
"::="
Value
ParameterizedValueSetTypeAssignment ::=
typereference
ParameterList
Type
"::="
ValueSet
ParameterizedObjectClassAssignment ::=
objectclassreference
ParameterList
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ISO/IEC 8824-4 : 2005 (E)
"::="
ObjectClass
ParameterizedObjectAssignment ::=
objectreference
ParameterList
DefinedObjectClass
"::="
Object
ParameterizedObjectSetAssignment ::=
objectsetreference
ParameterList
DefinedObjectClass
"::="
ObjectSet
8.3 A "ParameterList" is a list of "Parameter"s between braces:
ParameterList ::= "{" Parameter "," + "}"
Each "Parameter" consists of a "DummyReference" and possibly a "ParamGovernor":
Parameter ::= ParamGovernor ":" DummyReference | DummyReference
ParamGovernor ::= Governor | DummyGovernor
Governor ::= Type | DefinedObjectClass
DummyGovernor ::= DummyReference
DummyReference ::= Reference
A "DummyReference" in "Parameter" may stand for:
a) a "Type" or "DefinedObjectClass", in which case there shall be no "ParamGovernor";
b) a "Value" or "ValueSet", in which case the "ParamGovernor" shall be present, and in case
"ParamGovernor" is a "Governor" it shall be a "Type", and in case "ParamGovernor" is a
"DummyGovernor" the actual parameter for the "ParamGovernor" shall be a "Type";
c) an "Object" or "ObjectSet", in which case the "ParamGovernor" shall be present, and in case
"ParamGovernor" is a "Governor" it shall be a "DefinedObjectClass", and in case "ParamGovernor" is a
"DummyGovernor" the actual parameter for the "ParamGovernor" shall be a "DefinedObjectClass".
A "DummyGovernor" shall be a "DummyReference" that has no "Governor".
8.4 The scope of a "DummyReference" appearing in a "ParameterList" is the "ParameterList" itself, together with
that part of the "ParameterizedAssignment" which follows the "ParameterList". The "DummyReference" hides any other
"Reference" with the same name in that scope in any given instantiation.
NOTE – This subclause does not apply to "identifier"s defined in "NamedNumberList"s, "Enumeration"s and "NamedBitList"s,
since they are not "Reference"s. The "DummyReference" does not hide these "identifier"s (see Rec. ITU-T X.680 | ISO/IEC
8824-1, 19.12 and 20.11).
8.5 The usage of a "DummyReference" within its scope shall be consistent with its syntactic form, and, where
applicable, governor, and all usages of the same "DummyReference" shall be consistent with one another.
NOTE – Where the syntactic form of a dummy reference name is ambiguous (for example, between whether it is an
"objectclassreference" or "typereference"), the ambiguity can normally be resolved on the first use of the dummy reference name
on the right-hand side of the assignment statement. Thereafter, the nature of the dummy reference name is known. The nature of
the dummy reference is, however, not determined solely by the right-hand side of the assignment statement when it is in turn used
only as an actual parameter in a parameterized reference; in this case, the nature of the dummy reference must be determined by
examining the definition of this parameterized reference. Users of the notation are warned that such a practice can make ASN.1
specifications less clear, and it is suggested that adequate comments are provided to explain this for human readers.
Example
Consider the following parameterized object class assignment:
PARAMETERIZED-OBJECT-CLASS { TypeParam, INTEGER:valueParam, INTEGER:ValueSetParam } ::=
CLASS {
&valueField1 TypeParam,
&valueField2 INTEGER DEFAULT valueParam,
4 Rec. ITU-T X.683 (08/2015)

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ISO/IEC 8824-4 : 2005 (E)
&valueField3 INTEGER (ValueSetParam),
&ValueSetField INTEGER DEFAULT { ValueSetParam }
}
For the purpose of determining proper usage of the "DummyReference"s in the scope of the "Parameterized Assignment",
and for that purpose only, the "DummyReference"s can be regarded to be defined as follows:
TypeParam ::= UnspecifiedType
valueParam INTEGER ::= unspecifiedIntegerValue
ValueSetParam INTEGER ::= { UnspecifiedIntegerValueSet }
where:
a) TypeParam is a "DummyReference" which stands for a "Type". Therefore TypeParam can be used
wherever a "typereference" can be used, e.g. as a "Type" for the fixed-type value field valueFi
...