ISO/IEC 8824-3:2008
(Main)Information technology — Abstract Syntax Notation One (ASN.1): Constraint specification — Part 3:
Information technology — Abstract Syntax Notation One (ASN.1): Constraint specification — Part 3:
ISO/IEC 8824-3:2008 is part of Abstract Syntax Notation One (ASN.1) and provides notation for specifying user-defined constraints, table constraints, and contents constraints.
Technologies de l'information — Notation de syntaxe abstraite numéro un (ASN.1): Spécification des contraintes — Partie 3:
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 8824-3
Fourth edition
2008-12-15
Information technology — Abstract
Syntax Notation One (ASN.1): Constraint
specification
Technologies de l'information — Notation de syntaxe abstraite numéro
un (ASN.1): Spécification des contraintes
Reference number
ISO/IEC 8824-3:2008(E)
©
ISO/IEC 2008
---------------------- Page: 1 ----------------------
ISO/IEC 8824-3:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's 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 copyright@iso.org
Web www.iso.org
Published by ISO in 2009
Published in Switzerland
ii © ISO/IEC 2008 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 8824-3:2008(E)
CONTENTS
Page
Foreword .iv
Introduction. v
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 Parameterization of ASN.1 specification . 1
3.4 Additional definitions . 1
4 Abbreviations . 2
5 Convention . 2
6 Notation. 2
6.1 Constraint. 2
7 ASN.1 lexical items. 2
7.1 Additional keywords. 2
8 General constraint specification . 3
9 User-defined constraints. 3
10 Table constraints, including component relation constraints . 4
11 Contents constraints . 7
Annex A Constraining instance-of types. 8
A.4 Example . 8
Annex B Summary of the notation .9
© ISO/IEC 2008 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/IEC 8824-3:2008(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.
ISO/IEC 8824-3 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 Rec. X.682 (11/2008).
This fourth edition cancels and replaces the third edition (ISO/IEC 8824-3:2002), which has been technically
revised.
ISO/IEC 8824 consists of the following parts, under the general title Information technology — Abstract Syntax
Notation One (ASN.1):
⎯ Part 1: Specification of basic notation
⎯ Part 2: Information object specification
⎯ Part 3: Constraint specification
⎯ Part 4: Parameterization of ASN.1 specifications
iv © ISO/IEC 2008 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/IEC 8824-3:2008(E)
Introduction
Application designers require a notation to define a structured data type to convey their semantics. This is provided in
ITU-T Rec. X.680 | ISO/IEC 8824-1 and ITU-T Rec. X.681 | ISO/IEC 8824-2. A notation is also required to further
constrain the values that can appear. Examples of such constraints are restricting the range of some component(s), or
using a specified information object set to constrain an "ObjectClassFieldType" component, or using the "AtNotation"
to specify a relation between components.
This Recommendation | International Standard provides the notation for the general case of constraint specification.
NOTE 1 – For historical reasons the special case of a "subtype constraint" is specified in ITU-T Rec. X.680 | ISO/IEC 8824-1.
Constraint notation can appear (in round brackets) after any use of the syntactic construct "Type", and the purpose of
this Recommendation | International Standard is to specify the general case of what goes in the round brackets.
NOTE 2 – Multiple constraints (each inside its own round brackets) can be applied to the same "Type", as the result of
constraining a "Type" is itself formally a "Type" construct.
When a constraint is applied to the textually outermost use of a "Type" construct, it results in the creation of a new type
which is a subtype of the original (parent) type.
A subtype of a parent type can itself be used in defining other subtypes of the same parent type in other uses of the
constraint notation. Thus the subset of values constituting a subtype can be defined either by limiting the range of the
parent type, or by specifying the subtype as a union of sets of values.
NOTE 3 – The "ValueSet" notation specified in ITU-T Rec. X.680 | ISO/IEC 8824-1, 16.7, provides a further means of
specifying a subtype.
Constraints may also be used to produce a subtype of a parent type (as described above) when the notation is embedded
within another type. However, some "component relation" constraints are textually included following a "Type" (within
a set or sequence type definition), but are not used to restrict the set of possible values of the "Type" which they follow
(the referencing component). Rather, they specify a relation between the value of the referencing component and the
value of one or more other "Type"s in the same set or sequence type (called the referenced components).
Component relation constraints can be seen as subtyping the sequence type within which they are embedded, but not
necessarily the referencing type.
A constraint on an "ObjectClassFieldType" component can be applied by restricting the type or values in the
component by using an information object set. Such constraints are called table constraints, since they are specified in
terms of the "associated table" of the object set. The component relation constraints defined in this Recommendation |
International Standard are a special case of table constraints.
Finally, a "Type" may be subtyped by specifying the set of values in the subtype by human-readable text. Such a
constraint is called a user-defined constraint. For example, a user-defined constraint can be specified to constrain a BIT
STRING to the set of values produced by the encryption of a value of a specified ASN.1 type.
It is the purpose of this Recommendation | International Standard to provide the notation to be used for specifying table
constraints (including component relation constraints), and user-defined constraints.
NOTE 4 – In general, full support for the specification of constraints in a flexible way (particularly component relation
constraints, subtyping constraints, and user-defined constraints with a formally defined body) would require notation with a
power comparable to that of programming languages. Such power can only be sensibly provided by the establishment of links
from the ASN.1 notation into some other defined computer language. This version of this Recommendation | International
Standard does not provide such links, and hence supports only a small number of constraining mechanisms.
While the embedding of notation defining constraints (subtypes and relationships) will frequently be the most
convenient form of specification (particularly for the simple subtyping of primitive components of structures), separate
(external) specification will sometimes be preferred, particularly where the constraints are being imposed by a separate
group from that which defined the basic protocol.
NOTE 5 – The parameterization defined in ITU-T Rec. X.683 | ISO/IEC 8824-4 is specifically designed to enable a piece of
ASN.1 specification (and in particular, a constraint) to be parameterized, allowing the actual constraint to be imposed by some
other group that provides actual parameters for the parameterized construct.
© ISO/IEC 2008 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/IEC 8824-3:2008(E)
The notations for constraint specification supported here are:
– user-defined constraints (see clause 9);
– table constraints, including component relation constraints between two components which are
carrying values related to an information object, defined using the notation of ITU-T Rec. X.681 |
ISO/IEC 8824-2 (see clause 10);
– contents constraints (see clause 11).
The application of table constraints to the "InstanceOfType" construct of ITU-T Rec. X.681 | ISO/IEC 8824-2, Annex
C, is specified in Annex A.
vi © ISO/IEC 2008 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/IEC 8824-3:2008 (E)
INTERNATIONAL STANDARD
ISO/IEC 8824-3 : 2008 (E)
ITU-T Rec. X.682 (2008 E)
ITU-T RECOMMENDATION
Information technology –
Abstract Syntax Notation One (ASN.1):
Constraint specification
1 Scope
This Recommendation | International Standard is part of Abstract Syntax Notation One (ASN.1) and provides notation
for specifying user-defined constraints, table constraints, and contents constraints.
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
– ITU-T Recommendation X.680 (2008) | ISO/IEC 8824-1:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Specification of basic notation.
– ITU-T Recommendation X.681 (2008) | ISO/IEC 8824-2:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Information object specification.
– ITU-T Recommendation X.683 (2008) | ISO/IEC 8824-4:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Parameterization of ASN.1 specifications.
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 ITU-T Rec. X.680 | ISO/IEC 8824-1.
3.2 Information object specification
This Recommendation | International Standard uses the terms defined in ITU-T Rec. X.681 | ISO/IEC 8824-2.
3.3 Parameterization of ASN.1 specification
This Recommendation | International Standard uses the following term defined in ITU-T Rec. X.683 | ISO/IEC 8824-4:
– parameterized type.
3.4 Additional definitions
3.4.1 component relation constraint: A constraint on the values of a set type or sequence type which is textually
associated with one of the component types (the referencing component) of the set type or sequence type, and which
ITU-T Rec. X.682 (11/2008) 1
---------------------- Page: 7 ----------------------
ISO/IEC 8824-3:2008 (E)
specifies the relationship between the value of that component and the values of one or more other components (the
referenced components).
3.4.2 constrained type: The innermost "Type" which contains the referencing component and all of the referenced
components of some component relation constraint.
3.4.3 constraining set: The information object set referenced in some component relation constraint.
3.4.4 constraining table: The associated table (see ITU-T Rec. X.681 | ISO/IEC 8824-2, clause 13) corresponding
to a constraining set.
3.4.5 referenced component: A component of a set type or sequence type identified in a component relation
constraint.
3.4.6 referencing component: A component of a set type or sequence type which has an associated component
relation constraint.
3.4.7 selected rows: Those rows of a constraining table which contain, in the appropriate columns, the values of all
of the referenced components.
3.4.8 table constraint: A constraint applied to an object class field type which demands that its values conform to
the contents of the appropriate column of some table.
3.4.9 user-defined constraint: A constraint which requires a more complicated statement than can be
accommodated by the other forms of constraint, and which must therefore involve specification by some means outside
of ASN.1.
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 ITU-T Rec. X.680 |
ISO/IEC 8824-1, clause 5.
6 Notation
This clause summarizes the notation defined in this Recommendation | International Standard.
6.1 Constraint
The following notation which can be used as an alternative for "ConstraintSpec" (see ITU-T Rec. X.680 |
ISO/IEC 8824-1, 49.6) is defined in this Recommendation | International Standard:
– GeneralConstraint (see 8.1).
7 ASN.1 lexical items
In addition to the lexical items specified in ITU-T Rec. X.680 | ISO/IEC 8824-1, clause 12, this Recommendation |
International Standard makes use of the lexical items specified in the following subclauses. The general rules applicable
to these lexical items are as defined in ITU-T Rec. X.680 | ISO/IEC 8824-1, 12.1. These new lexical items make use of
the ASN.1 character set, as specified in ITU-T Rec. X.680 | ISO/IEC 8824-1, clause 11.
7.1 Additional keywords
The names CONSTRAINED, CONTAINING, ENCODED and BY are listed in ITU-T Rec. X.680 | ISO/IEC 8824-1, 12.38, as
reserved words.
2 ITU-T Rec. X.682 (11/2008)
---------------------- Page: 8 ----------------------
ISO/IEC 8824-3:2008 (E)
8 General constraint specification
8.1 The notation for a "GeneralConstraint" is as follows:
GeneralConstraint ::=
UserDefinedConstraint
| TableConstraint
| ContentsConstraint
8.2 The various possibilities for specification of the constraint are defined as follows:
a) "UserDefinedConstraint", in clause 9;
b) "TableConstraint", in clause 10;
c) "ContentsConstraint", in clause 11.
9 User-defined constraints
NOTE 1 – This form of constraint specification can be regarded as a special form of ASN.1 comment, since it is not fully
machine-processable. However, it would be possible for an automatic tool to use the presence of a particular user-defined
constraint to invoke user-supplied constraint checking.
NOTE 2 – Protocol designers should be aware that since the definition of a constraint in this way is not fully machine-
processable, a specification which employs this capability may be less easy to handle with automatic tools.
9.1 A user-defined constraint is specified by the syntax:
UserDefinedConstraint ::=
CONSTRAINED BY "{" UserDefinedConstraintParameter "," * "}"
9.2 It is recommended that the actual constraint be referenced by a comment anywhere inside the braces
( "{" and "}" ). This comment should clearly sta
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.