ISO/IEC 9834-1:2008

INTERNATIONAL ISO/IEC
STANDARD 9834-1
Third edition
2008-12-15
Information technology — Open Systems
Interconnection — Procedures for the
operation of OSI Registration Authorities:
General procedures and top arcs of the
International Object Identifier tree
Technologies de l'information — Interconnexion de systèmes ouverts
(OSI) — Procédures opérationnelles pour les organismes
d'enregistrement de l'OSI: Procédures générales et arcs sommitaux de
l'arborescence des identificateurs d'objet internationale

Reference number
©
ISO/IEC 2008
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ii © ISO/IEC 2008 – All rights reserved

CONTENTS
Page
1 Scope. 1

2 Normative references . 1

2.1 Identical Recommendations | International Standards. 1
2.2 Paired Recommendations | International Standards equivalent in technical content. 2

2.3 Additional references. 2
3 Definitions . 2

3.1 Organization definition. 2

3.2 OSI reference model terms. 3
3.3 Application layer structure terms. 3

3.4 ASN.1 terms . 3
3.5 Directory terms. 3

3.6 Unicode terms . 3
3.7 Additional definitions . 4

4 Abbreviations . 6

5 Notation . 6
6 Registration. 6

6.1 Overview. 6
6.2 Management of the registration naming domain . 7

6.3 Operation . 7

7 Registration-hierarchical-names . 7
7.1 The generic RH-name-tree. 7

7.2 The specific RH-name-tree for OIDs. 8
8 International Registration Authorities . 10

8.1 Requirement for an International Registration Authority. 10

8.2 Operation of International Registration Authorities. 10
8.3 Sponsoring Authorities. 11

9 Contents of registration procedures for objects of a particular type . 11
10 Progression of registration procedures for objects of a particular type . 12

11 Recommended fee structure. 13

Annex A – The top-level arcs of the OID tree. 14
A.1 General . 14

A.2 Assignment of primary integer values, Unicode labels and secondary identifiers to root arcs. 14
A.3 Assignment of primary integer values, Unicode labels and secondary identifiers to arcs

administered by ITU-T. 14
A.4 Assignment of primary integer values, Unicode labels and secondary identifiers to arcs

administered by ISO . 16
A.5 Assignment of OID components jointly administered by ISO and ITU-T . 18

A.6 Assignment of additional Unicode labels and secondary identifiers to the root arcs . 18

A.7 Assignment of additional Unicode labels from the root to lower-level arcs (long arcs) . 20
A.8 Publication of register entries requiring joint ITU-T and ISO approval . 21

Annex B – Derivation of Directory names. 22
Annex C – Derivation together of object identifiers and Directory names. 24
Annex D – Object identifier based Directory names. 25

D.1 Transformation of object identifiers into Directory names . 25
D.2 The use of object-identifier-based Directory names. 25

Annex E – References to this Recommendation | International Standard . 27

© ISO/IEC 2008 – All rights reserved iii

Page
Annex F – The IETF "oid" URI/IRI scheme . 29

F.1 General . 29
F.2 Information provided to IANA for registration of the "oid" scheme name. 29

F.3 Syntax of IRIs in the "oid" IRI scheme, specified using ASN.1 BNF. 30
F.4 Syntax of IRIs in the "oid" URI/IRI scheme using ABNF. 31

F.5 Semantics of IRIs in the "oid" IRI scheme. 31
B ibliography. 32

iv © ISO/IEC 2008 – All rights reserved

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 9834-1:2009 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.660 (08/2008).
This third edition cancels and replaces the second edition (ISO/IEC 9834-1:2005), which has been technically
revised.
ISO/IEC 9834 consists of the following parts, under the general title Information technology — Open Systems
Interconnection — Procedures for the operation of OSI Registration Authorities:
⎯ Part 1: General procedures and top arcs of the International Object Identifier tree
⎯ Part 2: Registration procedures for OSI document types
⎯ Part 3: Registration of Object Identifier arcs beneath the top-level arc jointly administered by ISO and
ITU-T
⎯ Part 4: Register of VTE Profiles
⎯ Part 5: Register of VT Control Object Definitions
⎯ Part 6: Registration of application processes and application entities
⎯ Part 7: Joint ISO and ITU-T Registration of International Organizations
⎯ Part 8: Generation and registration of Universally Unique Identifiers (UUIDs) and their use as ASN.1
Object Identifier components
⎯ Part 9: Registration of object identifier arcs for applications and services using tag-based identification

© ISO/IEC 2008 – All rights reserved v

INTERNATIONAL STANDARD
ITU-T RECOMMENDATION
Information technology – Open Systems Interconnection – Procedures for
the operation of OSI Registration Authorities: General procedures
and top arcs of the International Object Identifier tree

1 Scope
This Recommendation | International Standard:
a) specifies a registration-hierarchical-name-tree (RH-name-tree) which is a generic tree structure for
allocations made by a hierarchical structure of Registration Authorities, and the specific form of this that
supports the ASN.1 OBJECT IDENTIFIER type and the ASN.1 OID-IRI type (see ITU-T Rec. X.680 |
ISO/IEC 8824-1);
b) registers top-level arcs of the international object identifier tree;
c) specifies procedures which are generally applicable to registration in the context of any RH-name-tree;
d) provides guidelines for the establishment and operation of International Registration Authorities for use,
when needed, by other Recommendations and/or International Standards;
e) provides guidelines for additional Recommendations | International Standards which choose to reference
the procedures in this Recommendation | International Standard;
f) provides a recommended fee structure for lower-level Registration Authorities;
g) records the information provided to IETF and the registration with IANA of the "oid" IRI scheme (see
Annex F).
NOTE 1 – This Recommendation | International Standard does not exclude or disallow the use of any syntactic form of names or
naming domains for registration purposes. This Recommendation | International Standard is intended to cover those cases where
a registration-hierarchical-name is an appropriate form of identification.
NOTE 2 – Information about registration for specific objects is contained in separate Recommendations | International Standards.
This Recommendation | International Standard applies to registration by Recommendations and/or International
Standards, by International Registration Authorities (see clause 8), and by any other Registration Authority.
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.207 (1993) | ISO/IEC 9545:1994, Information technology – Open Systems
Interconnection – Application layer structure.
– ITU-T Recommendation X.500 (2008) | ISO/IEC 9594-1:2008, Information technology – Open Systems
Interconnection – The Directory: Overview of concepts, models and services.
– ITU-T Recommendation X.501 (2005) | ISO/IEC 9594-2:2005, Information technology – Open Systems
Interconnection – The Directory: Models.
– ITU-T Recommendation X.520 (2005) | ISO/IEC 9594-6:2005, Information technology – Open Systems
Interconnection – The Directory: Selected attribute types.
– ITU-T Recommendation X.650 (1996) | ISO/IEC 7498-3:1997, Information technology – Open Systems
Interconnection – Basic Reference Model: Naming and addressing.
ITU-T Rec. X.660 (08/2008) 1
– ITU-T Recommendation X.662 (2008) | ISO/IEC 9834-3:2008, Information technology – Open Systems
Interconnection – Procedures for the operation of OSI Registration Authorities: Registration of object
identifier arcs beneath the top-level arc jointly administered by ISO and ITU-T.
– 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.690 (2008) | ISO/IEC 8825-1:2008, Information technology – ASN.1
encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER), and
Distinguished Encoding Rules (DER).
– ITU-T Recommendation X.722 (1992) | ISO/IEC 10165-4:1992, Information technology – Open Systems
Interconnection – Structure of management information: Guidelines for the definition of managed
objects.
2.2 Paired Recommendations | International Standards equivalent in technical content
– ITU-T Recommendation F.400/X.400 (1999), Message handling system and service overview.
ISO/IEC 10021-1:2003, Information technology – Message Handling Systems (MHS) – Part 1: System
and service overview.
2.3 Additional references
– ITU-T Recommendation X.121 (2000), International numbering plan for public data networks.
– IETF RFC 3987 (2005), Internationalized Resource Identifiers (IRIs).
– ISO 3166-1:2006, Codes for the representation of names of countries and their subdivisions – Part 1:
Country codes.
– ISO 3166-3:1999, Codes for the representation of names of countries and their subdivisions – Part 3:
Codes for formerly used names of countries.
– ISO/IEC 6523-1:1998, Information technology – Structure for the identification of organizations and
organization parts – Part 1: Identification of organization identification schemes.
– ISO/IEC 6523-2:1998, Information technology – Structure for the identification of organizations and
organization parts – Part 2: Registration of organization identification schemes.
– ISO 8571-1:1988, Information processing system – Open Systems Interconnection – File transfer, Access
and Management – Part 1: General introduction.
– ISO/IEC 10646:2003, Information technology – Universal Multiple-Octet Coded Character Set (UCS).
NOTE – ITU-T Rec. T.55 [3] recommends the use of ISO/IEC 10646 for the representation of the languages of
the world.
– W3C XML Namespaces:2006, Namespaces in XML, W3C Recommendation, Copyright © [16 August
2006] World Wide Web Consortium, (Massachusetts Institute of Technology, Institut National de
Recherche en Informatique et en Automatique, Keio University),
http://www.w3.org/TR/2006/REC-xml-names-20060816.
3 Definitions
For the purposes of this Recommendation | International Standard, the following definitions apply.
3.1 Organization definition
This Recommendation | International Standard uses the following term defined in ISO/IEC 6523-1:
a) organization.
2 ITU-T Rec. X.660 (08/2008)
3.2 OSI reference model terms
This Recommendation | International Standard uses the following terms defined in ITU-T Rec. X.650 |
ISO/IEC 7498-3:
a) name;
b) naming authority;
c) naming domain;
d) synonym.
3.3 Application layer structure terms
This Recommendation | International Standard uses the following terms defined in ITU-T Rec. X.207 | ISO/IEC 9545:
a) application-entity-title;
b) application-process-title.
3.4 ASN.1 terms
3.4.1 This Recommendation | International Standard uses the following terms defined in ITU-T Rec. X.680 |
ISO/IEC 8824-1:
a) (ASN.1) identifier
b) object;
c) object descriptor type;
d) (ASN.1) object identifier type;
e) OID internationalized resource identifier type.
3.4.2 This Recommendation | International Standard uses the following term defined in ITU-T Rec. X.681 |
ISO/IEC 8824-2:
a) information object.
3.5 Directory terms
3.5.1 This Recommendation | International Standard uses the following terms defined in ITU-T Rec. X.500 |
ISO/IEC 9594-1:
a) Directory;
b) Directory name.
3.5.2 This Recommendation | International Standard uses the following terms defined in ITU-T Rec. X.501 |
ISO/IEC 9594-2:
a) attribute;
b) attribute type;
c) attribute value;
d) attribute value assertion;
e) object class;
f) relative distinguished name.
3.6 Unicode terms
This Recommendation | International Standard uses the following terms defined in ISO/IEC 10646:
a) coded character;
b) graphics character.
ITU-T Rec. X.660 (08/2008) 3
3.7 Additional definitions
3.7.1 additional secondary identifier: A secondary identifier for a top-level arc of the international object
identifier tree that is assigned from time to time by a simple Resolution of both the relevant ITU-T study group and the
relevant ISO/IEC JTC 1 Sub-Committee, without requiring any change to this or any other Recommendation and/or
International Standard (see A.6.4).
3.7.2 additional Unicode label: A Unicode label for one of the top-level arcs of the international object identifier
tree that is assigned from time to time by a simple Resolution of both the relevant ITU-T study group and the relevant
ISO/IEC JTC 1 Sub-Committee, without requiring any change to this or any other Recommendation | International
Standard (see A.6.4).
3.7.3 administrative role (of a Registration Authority): Assigning and making available unambiguous names
according to the Recommendation | International Standard defining the procedures for the Registration Authority (at
whatever depth).
3.7.4 integer-valued Unicode label: A Unicode label for an arc that is the character representation (with no leading
zeros) of the primary integer value of that arc.
NOTE – An arc of the international object identifier tree can have no other Unicode label that is the character representation
(with or without leading zeros) of an integer value (see 7.2.4).
3.7.5 International Registration Authority: A Registration Authority (see 3.7.17) acting at the international level
where the procedures for its operation, defined in a relevant Recommendation and/or International Standard, declare it
to operate as an International Registration Authority (see clause 8).
3.7.6 International Object Identifier tree: A specific form of an RH-name-tree whose root corresponds to this
Recommendation | International Standard and whose nodes correspond to registration authorities responsible for
allocating arcs from a parent node.
3.7.7 IRI/URI value: A value that identifies a resource using one of the schemes registered with IANA for URIs.
3.7.8 Joint ITU-T | ISO/IEC JTC 1 Collaborative Team for object identifiers: A group established in
accordance with ITU-T Rec. A.23, Annex A and ISO/IEC JTC 1 Directives Edition 5 Version 2.0, subclause 2.6.4 and
Annex K, clause 8 to progress work on Joint Text in relation to object identifiers (OIDs).
3.7.9 long arc: A Unicode label from a superior node in the international object identifier tree that identifies a node
that is not immediately beneath the superior node.
NOTE 1 – The long arc (in addition to normal arcs) has to satisfy the unambiguity requirements for all arcs from that superior
node (see 7.2.8).
NOTE 2 – The only property of a long arc (see 3.7.15) is its Unicode label. It does not have a primary integer value or a
secondary identifier. It is essentially a short-cut for a series of arcs, each of which has a primary integer value and its own
Unicode labels.
NOTE 3 – The long arc can therefore not be used to define the value of an (ASN.1) object identifier type. It can only be used in
an OID internationalized resource identifier (see 3.7.12).
3.7.10 object (of interest): Anything in some world, generally the world of telecommunications and information
processing or some part thereof,
a) which is identifiable (can be named); and
b) which may be registered.
NOTE – Examples of objects are ASN.1 modules (see ITU-T Rec. X.680 | ISO/IEC 8824-1), information objects (see ITU-T
Rec. X.681 | ISO/IEC 8824-2), managed objects (see ITU-T Rec. X.722 | ISO/IEC 10165-4), XML namespaces (see W3C XML
Namespaces) and any other object that can be identified by an OID, URI or IRI.
3.7.11 object identifier: An ordered list of primary integer values from the root of the international object identifier
tree to a node, which unambiguously identifies that node (see 7.2.8).
3.7.12 OID internationalized resource identifier: An IRI/URI value constrained to the IANA "oid" IRI/URI
scheme (see Annex F)
NOTE 1 – This is semantically an ordered list of Unicode labels, from the root of the international object identifier tree, that
unambiguously identifies the node for a resource (see 7.2.8)
NOTE 2 – The ASN.1 OID-IRI type (see ITU-T Rec. X.680 | ISO/IEC 8824-1) is the set of all OID international resource
identifier values, and provides value notations for all OID international resource identifiers based on the international object
identifier tree. Corresponding encodings are specified in the ITU-T Rec. X.690 series | ISO/IEC 8825 multipart Standard.
3.7.13 primary integer value: A primary value of type integer used to unambiguously identify an arc of the
international object identifier tree.
NOTE – An arc of the international object identifier tree has precisely one primary integer value, apart from long arcs, that have
only Unicode labels.
4 ITU-T Rec. X.660 (08/2008)
3.7.14 primary value: A value of a specified type assigned to an arc of the RH-name-tree that can provide an
unambiguous identification of that arc within the set of arcs from its superior node.
3.7.15 properties of an arc: The primary integer value and the Unicode labels and secondary identifiers assigned to
that arc.
NOTE – Long arcs (see 3.7.9) have only Unicode labels. All other arcs have precisely one primary integer value.
3.7.16 registration: The assignment of an unambiguous name to an object in a way which makes the assignment
available to interested parties.
3.7.17 Registration Authority: An entity such as an organization, a standard or an automated facility that performs
registration of one or more types of objects (see also 3.7.5).
NOTE – For this Recommendation | International Standard, the above definition of registration authority extends the term to
cover registration by organizations acting at international, regional and national levels and by other means.
3.7.18 registration-hierarchical-name: A name which is unambiguous within the registration-hierarchical-
name-tree and which is assigned by registration. The semantic form of this name is structured according to the rules in
clause 6.
3.7.19 registration-hierarchical-name-tree: A tree whose nodes correspond to objects that are registered and
whose non-leaf nodes may be registration authorities.
3.7.20 registration procedures: The specified procedures for performing registration and amending (or deleting)
existing registrations.
3.7.21 relevant ITU-T study group: The ITU-T study group that is responsible for the Joint ITU-T | ISO/IEC JTC 1
Collaborative Team for object identifiers.
3.7.22 relevant ISO/IEC JTC 1 Sub-Committee: The ISO/IEC JTC 1 Sub-Committee that is responsible for the
Joint ITU-T | ISO/IEC JTC 1 Collaborative Team for object identifiers.
3.7.23 root arc: One of the three arcs from the root of the international object identifier tree.
3.7.24 secondary identifier: A secondary value restricted to the characters forming an (ASN.1) identifier (see
ITU-T Rec. X.680 | ISO/IEC 8824-1), assigned either in an ITU-T Recommendation, an International Standard or by
some other Registration Authority to an arc of the OID tree.
NOTE – An arc of the international object identifier tree can have zero or more secondary identifiers.
3.7.25 secondary value: A value of some type associated with an arc that provides additional identification useful
for human readers, but that does not in general unambiguously identify that arc, and is not normally included in
computer communications.
3.7.26 sponsoring authority: An organization recognized to receive proposals for registration and to submit
applications to an International Registration Authority as defined by a given Recommendation and/or International
Standard (see 8.2 and 8.3).
3.7.27 technical role (of a registration authority): Verifying that these definitions are in accordance with the
Recommendation and/or International Standard defining the form of the definition.
3.7.28 top-level arcs (top arcs): The subset of arcs of the international object identifier tree that are assigned
identifiers in this Recommendation | International Standard (supplemented by references to the ITU-T Rec. X.660 series
| ISO/IEC 9834 multipart Standards, or by a Resolution from time to time of both the relevant ITU-T study group and
the relevant ISO/IEC JTC 1 Sub-committee).
3.7.29 Unicode character: A character from the Unicode character set.
3.7.30 Unicode character set: The set of coded characters specified in ISO/IEC 10646.
NOTE – This is the same character set as that defined by the Unicode Consortium in [4].
3.7.31 Unicode label: A primary value that consists of an unbounded sequence of Unicode characters that does not
contain the SPACE character (see 7.2.5 for other restrictions) used to unambiguously identify an arc of the ASN.1 tree.
NOTE 1 – Unicode labels are always case sensitive for matching purposes and when determining unambiguity.
NOTE 2 – An arc of the international object identifier tree can have multiple Unicode labels.
NOTE 3 – Joint action by ITU-T and ISO/IEC can also allocate a Unicode label for a long arc that identifies a node which is two
levels beneath the root (see A.7).
ITU-T Rec. X.660 (08/2008) 5
4 Abbreviations
For the purposes of this Recommendation | International Standard, the following abbreviations apply:
ACSE Association Control Service Element
ASN.1 Abstract Syntax Notation One
DCC Data Country Code
DIT Directory Information Tree
DNIC Data Network Identification Code
DSA Directory System Agent
DUA Directory User Agent
FTAM File Transfer, Access and Management
IANA Internet Assigned Numbers Authority
ICD International Code Designator
IRI Internationalized Resource Identifier
ISP International Standardized Profile
MHS Message Handling Systems
OID Object Identifier
OID-IRI OID Internationalized Resource Identifier
OSI Open Systems Interconnection
RA Registration Authority
RDN Relative Distinguished Name
RH-name Registration-Hierarchical-name
RH-name-tree Registration-Hierarchical-name-tree
ROA Recognized Operating Agency
TSB Telecommunication Standardization Bureau
URI  Uniform Resource Identifier
5 Notation
5.1 Unicode characters are specified in two ways. For a single character, it is normal to use the Unicode name in a
special font followed by the word "character". For example:
SPACE character
5.2 For a range of characters, it is normal to use the letter U followed by eight hex digits for the start and end of
the range (both in a special font) in accordance with the notation defined in ISO/IEC 10646. For example:
U0000F900 to U0000FDCF
6 Registration
6.1 Overview
6.1.1 Many Recommendations | International Standards define certain objects for which unambiguous identification
is required. This is achieved by registration.
NOTE – Examples of these objects are given in 3.7.10.
6.1.2 Registration is the assignment of a name to an object in a way which makes the assignment available to
interested parties. It is carried out by a registration authority.
6.1.3 Registration can be effected by a Recommendation | International Standard, by publishing in the
Recommendation | International Standard the names and the corresponding definitions of object. Such a mechanism
requires amendment of the Recommendation | International Standard for each registration, and hence is not appropriate
in cases where the registration activity is high.
6 ITU-T Rec. X.660 (08/2008)
6.1.4 Alternatively, registration can be effected by permitting one or more organizations to act as registration
authorities to perform registration on a flexible basis.
6.1.5 The form of name used (see 7.1.5) and the management of the registration naming domain ensure independent
assignment of unambiguous names by different registration authorities.
6.2 Management of the registration naming domain
6.2.1 The management of the entire registration naming domain is accomplished by a process of delegation of
authority. In this process, the registration authority responsible for a given naming domain may partition that naming
domain. In doing so, it may or may not delegate the registration responsibility for the naming domain formed by each
partition to a subordinate registration authority. The naming of a partition does not necessarily imply authority to
register objects under that partition. This delegation of registration responsibility can be applied repeatedly with a
subordinate registration authority partitioning further the naming domain for which it is responsible and delegating
responsibility for those partitions to the registration authorities subordinate to it.
6.2.2 The registration authority responsible for a given naming domain must assign a name to the partition of that
naming domain that a given sub-authority will manage. The name assigned shall be globally unambiguous, and shall be
concatenated as a prefix to all names assigned by that sub-authority. The repeated application of this process through a
hierarchy of registration agents ensures the generation of unambiguous names. The generation of names for registration
purposes is discussed further in clause 7.
NOTE – An organization, a Recommendation | International Standard or an automated facility can be the registration authority
for more than one partition of a naming domain.
6.3 Operation
6.3.1 A registration authority may concern itself only with unambiguous assignment of names (the administrative
role) or may in addition need to concern itself with recording definitions of objects and verifying that these definitions
are in accordance with the Recommendation | International Standard defining the form of the definition (the technical
role).
6.3.2 The criteria for registering an object may vary among registration authorities. It is the responsibility of each
authority to establish those criteria. A registration authority may also choose to define criteria for any authorities which
are subordinate to it.
NOTE – Among the criteria to be considered in the registration of an object is the level at which registration is appropriate. For
example, it may be that the definition of an object registered by a particular registration authority may find wide use beyond the
community serviced by that registration authority. Although the assigned name is globally unambiguous and can be used outside
that community, it may be desirable to restate the definition in the style acceptable to the larger community of interest. If so, the
restated definition should be registered with the registration authority appropriate for that larger community.
6.3.3 Synonyms are created when an instance of a type of object is registered more than once. There may be valid
reasons for creating synonyms, e.g., the Directory aliases. It is difficult to detect occurrences of synonyms. In case
where synonyms are undesirable, it may be possible to reduce the number by such means as technical review or
administrative fees (in the case of registration authorities). It must be decided in each case whether this is necessary and
practical.
NOTE – There is no practical way to ensure that the same object has not been registered by multiple registration authorities and
the procedures in this Recommendation | International Standard do not ensure that only a single name is assigned to an object.
7 Registration-hierarchical-names
7.1 The generic RH-name-tree
7.1.1 The RH-name-tree is a generic concept that applies to any form of hierarchical naming in which a name is
constructed by the concatenation of values of arcs starting from the root of a tree and proceeding to one of its leaves.
RH-name-trees differ in the sort of values assigned to arcs (typically names or numbers or attribute type-value pairs).
All of Directory names, MHS names, ASN.1 object identifiers and OID internationalized resource identifiers are
hierarchical names that are supported by a specific form of RH-name-tree.
7.1.2 The introduction here of the RH-name-tree concept is intended to make it possible to specify procedures that
are applicable to registration authorities related to all three naming conventions. The use of this term should be
restricted to standards that address at least two of the specific naming structures that the term RH-name-tree
encompasses.
ITU-T Rec. X.660 (08/2008) 7
7.1.3 All currently defined RH-name-trees (the OID tree, and trees supporting Directory names and MHS names)
are trees whose root corresponds to this Recommendation | International Standard and whose leaf and non-leaf nodes
correspond to objects that are registered. Non-leaf nodes correspond to registration authorities where registration
responsibility has been delegated to them by a superior node.
7.1.4 The arcs from a given node to its immediate subordinates are unambiguously identified within the scope of
the node by each of one or more primary values of different types. These primary values are assigned by the registration
authority corresponding to the superior node. Thus, any path from the root to a node provides an unambiguous name for
that node by concatenating (in order) the primary values of a given type for the arcs on the path. An arc may also have
secondary values associated with it that are not necessary for the unambiguous identification of the arc, but that can
appear in human-readable notation (in addition to the primary values) in order to describe more clearly the nature of an
object identified by a path through the RH-name-tree.
NOTE – If any arc is not assigned a primary value of a given type, then the node identified by the arc and all of its subordinates
can only be referenced using names constructed with primary values of a different type.
7.1.5 In general, the types of values assigned by a registration authority can include integer values, alphanumeric
values and other types of values, but specific forms of the RH-name-tree generally restrict the types of values to be
used. The contents of character sets and composition rules for values formed at subordinate arcs should be defined in
registration authority procedure standards. The contents of character sets and composition rules may be further
constrained or extended by subordinate registration authorities taking into consideration the expected use of the
resulting values in different forms of name.
7.1.6 Where a given set of registration authorities assigns values of more than one type, the significance, if any, of
the relationship between the resultant names (generated as defined in 7.1.4) is outside the scope of this
Recommendation | International Standard.
7.1.7 The generation of some specific forms of name for registration purposes is defined in the normative annexes
to this Recommendation | International Standard. The generation of other forms of name is also defined in other
registration authority documents or in relevant Recommendations | International Standards.
7.2 The specific RH-name-tree for OIDs
7.2.1 The ASN.1 object identifier (OBJECT IDENTIFIER) and OID internationalized resource identifier (OID-IRI)
types, as specified in ITU-T Rec. X.680 | ISO/IEC 8824-1, are ASN.1 types whose abstract values are associated with a
specific form of RH-name-tree (the OID tree). The semantics of the values of these types are defined by reference to the
OID tree.
NOTE 1 – The ASN.1 OID-IRI type is more friendly for human reading, but the ASN.1 OBJECT IDENTIFIER type is more
efficient for binary transfers. Protocol designers will choose when to use an ASN.1 OBJECT IDENTIFIER type or an ASN.1
OID-IRI type.
NOTE 2 – For all objects in the OID tree, both ASN.1 OBJECT IDENTIFIER types and OID-IRI types are available for their
identification. This is because all arcs are required to have a primary integer value that automatically defines an integer-valued
Unicode label (see 7.2.4). The former can be used in OID values and the latter in OID-IRI values, even if there are no other
Unicode labels and no secondary identifiers.
7.2.2 Each arc of the OID tree shall be labelled with a primary integer value that automatically defines an integer-
valued Unicode label (see 7.2.4). It may also have zero or more non-integer Unicode labels, and zero or more secondary
identifiers. Some of the non-integer Unicode labels and secondary identifiers may be additional Unicode labels or
additional secondary identifiers.
NOTE – ITU-T Recommendations | International Standards (including this ITU-T Recommendation | International Standard)
assign a primary integer value (that defines an integer-valued Unicode label), a Unicode label that is not integer-valued, and a
secondary identifier to all top-level arcs. Additional Unicode labels and additional secondary identifiers are assigned from time to
time in accordance with A.6 (by a simple Resolution of the relevant ITU-T study group and of the relevant ISO/IEC JTC 1
Sub-Committee).
7.2.3 The integer-valued Unicode label shall contain no characters other than those in the range from the DIGIT
ZERO character to the DIGIT NINE character and shall not commence with a DIGIT ZERO character unless it has only
a single character and the primary integer value of the arc is zero.
7.2.4 The integer-valued Unicode label, when treated as the representation of an integer value in accordance with
normal conventions for the decimal representation of an integer value, shall produce the value of the primary integer
value.
7.2.5 A non-integer Unicode label shall satisfy the following constraints.
7.2.5.1 It shall contain at least one character that is not in the range DIGIT ZERO character to the DIGIT NINE
character.
8 ITU-T Rec. X.660 (08/2008)
7.2.5.2 It shall contain only the following characters, subject to 7.2.5.3:
HYPHEN-MINUS character
FULL STOP character
LOW LINE character
TILDE character
DIGIT ZERO to DIGIT NINE
LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z
LATIN SMALL LETTER A to LATIN SMALL LETTER Z
U000000A0 to U0000DFFE
U0000F900 to U0000FDCF
U0000FDF0 to U0000FFEF
U00010000 to U0001FFFD
U00020000 to U0002FFFD
U00030000 to U0003FFFD
U00040000 to U0004FFFD
U00050000 to U0005FFFD
U00060000 to U0006FFFD
U00070000 to U0007FFFD
U00080000 to U0008FFFD
U00090000 to U0009FFFD
U000A0000 to U000AFFFD
U000B0000 to U000BFFFD
U000C0000 to U000CFFFD
U000D0000 to U000DFFFD
U000E1000 to U000EFFFD
NOTE 1 – This allows all the characters that are not reserved in IETF RFC 3987.
NOTE 2 – The forbidden characters arise from their use (or reservation) for special purposes in ISO/IEC 10646.
7.2.5.3 Characters within the above ranges that are identified by ISO/IEC 10646 as "(This position shall not be used)"
are excluded from the range.
NOTE – Tool implementers should note that this designation may be removed in future versions of ISO/IEC 10646 and may
choose to be tolerant of violations of this constraint.
7.2.6 Primary integer values for arcs (and the corresponding integer-valued Unicode label) are unbounded, except
that:
a) the root arcs are restricted to three arcs with primary integer values 0 to 2; and
b) the arcs beneath the root arcs 0 and 1 are restricted to forty arcs with primary integer values 0 to 39.
NOTE – This enables optimized encodings to be used in which the primary integer values of the top-level arcs under root arcs 0
and 1, and arcs 0 to 47 under root arc 2 encode in a single octet in an ASN.1 object identifier encoding (see ITU-T Rec. X.690
series | ISO/IEC 8825 multipart Standard).
7.2.7 An arc may (but need not) also have assigned to it zero or more secondary identifiers and zero or more
additi
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