ISO/IEC 21000-3:2003

INTERNATIONAL ISO/IEC
STANDARD 21000-3
First edition
2003-04-01
Information technology — Multimedia
framework (MPEG-21) —
Part 3:
Digital Item Identification
Technologies de l'information — Cadre multimédia (MPEG-21) —
Partie 3: Identification des éléments digitaux

Reference number
©
ISO/IEC 2003
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ii © ISO/IEC 2003 — All rights reserved

Contents Page
Foreword. v
Executive Summary for MPEG-21 . vi
1 Scope. 1
1.1 Organisation of the Document . 1
1.2 Introduction to Digital Items . 2
1.3 Example of a Digital Item. 2
1.4 Relationship between Digital Item Declaration and Digital Item Identification . 2
1.5 Using Identifiers to Link Identifiers with Associated Information . 4
2 Normative references. 4
3 Terms and definitions. 5
3.1 Terms and definitions. 5
3.2 Abbreviations. 6
4 Identification of Digital Items and their Parts. 7
4.1 Identifier Element. 7
4.1.1 Syntax. 7
4.1.2 Semantics. 8
4.1.3 Notes (informative). 8
4.2 RelatedIdentifier Element . 8
4.2.1 Syntax. 8
4.2.2 Semantics. 8
4.2.3 Example. 9
4.3 Type Element. 9
4.3.1 Syntax. 9
4.3.2 Semantics. 9
4.3.3 Example. 9
4.4 Digital Item Identification XML Schema Definition . 9
4.5 Examples (informative). 10
4.5.1 Example: Identification of a Music Release . 10
4.5.2 Example: Referring to Digital Item in external DID Document . 10
4.5.3 Example: Referring to Resources stored on external server. 12
4.5.4 Example: Identifying a Sound Recording and the related Underlying Musical Work. 12
4.5.5 Example: Identifying a Digital Item Type. 13
5 Identification of Description Schemes. 13
Annex A (normative) Requirements for the Registration Authority for Digital Item Identification
Systems. 14
A.1 Identifications Systems to be registered for use within ISO/IEC 21000. 14
A.2 Procedure for Requesting an Identification System Identifier for use within ISO/IEC 21000 . 14
A.3 Responsibilities of the Registration Authority. 14
A.4 Contact information for the Registration Authority . 15
A.5 Responsibilities of Parties Requesting a Identification System within ISO/IEC 21000 . 15
A.6 Appeal Procedure for Denied Applications. 15
A.7 Registration Application Form. 16
Annex B (informative) Interoperability Considerations on Resolution Systems. 17
B.1 Introduction. 17
B.2 Necessary Functions and Resolution System Switcher. 17
B.3 An Overall Example of a DID Browsing System with Resolution System Switcher . 19
B.4 Summary. 19
Annex C (informative) List of existing Identification and Description Schemes . 20
© ISO/IEC 2003 — All rights reserved iii

C.1 Common Information System – CIS .20
C.2 Content ID Forum – cIDf .20
C.3 Digital Object Identifier – DOI.21
C.4 Dublin Core Metadata Initiative – DCMI .22
C.5 The EAN/UCC System.22
C.6 Global Release Identifier – GRID .22
C.7 Identifier for Versions of Audiovisual works – V-ISAN.23
C.8 International Standard Audiovisual Number – ISAN .23
C.9 International Standard Book Number – ISBN.23
C.10 International Standard Recording Code – ISRC.24
C.11 International Standard Serial Number – ISSN .24
C.12 International Standard Textual Work Code – ISTC .25
C.13 International Standard Work Code – ISWC.25
C.14 INteroperability of Data in E-Commerce Systems – INDECS.26
C.15 ONline Information eXchange – ONIX International .26
C.16 URL-based Identification Schemes.27
Annex D (informative) Patent statements.29
Bibliography.30

iv © ISO/IEC 2003 — 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.
ISO/IEC 21000-3 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
ISO/IEC 21000 consists of the following parts, under the general title Information technology — Multimedia
framework (MPEG-21):
 Part 1: Vision, Technologies and Strategy
 Part 2: Digital Item Declaration
 Part 3: Digital Item Identification
 Part 4: Intellectual Property Management and Protection
 Part 5: Rights Expression Language
 Part 6: Rights Data Dictionary
 Part 7: Digital Item Adaptation
 Part 8: Reference Software
 Part 9: File Format
NOTE Other parts may be added in the future.

© ISO/IEC 2003 — All rights reserved v

Executive Summary for MPEG-21
Today, many elements exist to build an infrastructure for the delivery and consumption of multimedia content.
There is, however, no "big picture" to describe how these elements, either in existence or under development,
relate to each other. The aim for MPEG-21 is to describe how these various elements fit together. Where gaps
exist, MPEG-21 will recommend which new standards are required. ISO/IEC JTC 1/SC 29/WG 11 (MPEG) will
then develop new standards as appropriate while other relevant standards may be developed by other bodies.
These specifications will be integrated into the multimedia framework through collaboration between MPEG
and these bodies.
The result is an open framework for multimedia delivery and consumption, with both the content creator and
content consumer as focal points. This open framework provides content creators and service providers with
equal opportunities in the MPEG-21 enabled open market. This will also be to the benefit of the content
consumer providing them access to a large variety of content in an interoperable manner.
The vision for MPEG-21 is to define a multimedia framework to enable transparent and augmented use of
multimedia resources across a wide range of networks and devices used by different communities.
This third part of MPEG-21 (ISO/IEC 21000-3) specifies how Digital Items (see ISO/IEC 21000-2) and parts
and collections thereof can be uniquely identified.

vi © ISO/IEC 2003 — All rights reserved

INTERNATIONAL STANDARD ISO/IEC 21000-3:2003(E)

Information technology — Multimedia framework (MPEG-21) —
Part 3:
Digital Item Identification
1 Scope
This third part of MPEG-21 (ISO/IEC 21000-3), entitled Digital Item Identification (DII), specifies
 How to uniquely identify Digital Items (and parts thereof);
 How to uniquely identify IP related to the Digital Items (and parts thereof), for example abstractions;
 How to uniquely identify Description Schemes;
 The relationship between Digital Items (and parts thereof) and existing identification systems. Annex C
contains a list of relevant identification systems. This is not an exhaustive list and is subject to change
over time;
 The relationship between Digital Items (and parts thereof) and relevant description schemes. Annex C
contains a list of relevant description schemes. This is not an exhaustive list and is subject to change over
time.
ISO/IEC 21000-3 specification does not specify:
 New identification systems for the content elements for which identification and description schemes
already exist and are in use (e.g., ISO/IEC 21000-3 does not attempt to replace the ISRC, as defined in
ISO 3901, for sound recordings;
 Normative description schemes for describing content.
1.1 Organisation of the Document
This specification contains five Clauses and four Annexes:
The remainder of this Clause 1 contains an overview of MPEG-21 Digital Items and the relation between
parts 2 and 3 of ISO/IEC 21000. Clauses 2 and 3 contain normative references and a list of applicable terms
and definitions.
Clause 4 specifies how to uniquely identify Digital Items, how to associate related identifiers with Digital Items,
how to identify different types of Digital Items. Clause 0 then specifies how to associate metadata with Digital
Items by using description scheme identifiers.
The normative Annex A contains criteria that need to be fulfilled by a registration authority that is required for
the identification of Digital Items and their parts as specified in ISO/IEC 21000-3. Annex B contains an
informative example of how to resolve a unique identifier to appropriate metadata. Annex C contains an
informative list of existing identification schemes that can be used by this specification. Finally, Annex D
contains information of patent statements relating to this specification.
© ISO/IEC 2003 — All rights reserved 1

1.2 Introduction to Digital Items
Within any system (such as MPEG-21) that proposes to facilitate a wide range of actions involving “Digital
Items”, there is a need for a very precise description for defining exactly what constitutes such an “item”.
Clearly there are many kinds of content, and probably just as many possible ways of describing it to reflect its
context of use. This presents a strong challenge to lay out a powerful and flexible model for Digital Items
which can accommodate the myriad forms that content can take (and the new forms it will assume in the
future). Such a model is only truly useful if it yields a format that can be used to represent any Digital Items
defined within the model unambiguously and communicate them, and information about them, successfully.
The Digital Item Declaration specification (ISO/IEC 21000-2) provides such flexibility for representing Digital
Items.
1.3 Example of a Digital Item
This sub-clause provides a simple example of a Digital Item. More complex examples can be found in
ISO/IEC 21000-2.
This example uses ISO/IEC 21000 to create an "MPEG-21 Music Album" comprising a series of resources:
1)
 Three audio files (coded in MPEG-2 AAC , representing the "tracks" that form the basis of the album;
2)
 Two text files (in Unicode , representing the lyrics to two of the tracks;
3)
 Two images (in JPEG , representing the cover photograph and other artwork of the album;
4)
 A text file (in HTML , representing the introductory text for the album.
The relationship between these resources and how they relate to the Digital Item itself is expressed in the
5)
Digital Item Declaration (DID . The DID contains, besides the references to the resources, information about
the item and/or parts thereof. These metadata elements are associated through DID mechanisms to the
item/resources as shown in Figure 1 overleaf.
1.4 Relationship between Digital Item Declaration and Digital Item Identification
Identifiers covered by this specification can be associated with Digital Items, containers, components, and/or
fragments thereof by including them in a specific place in the Digital Item Declaration. This place is the
STATEMENT element. Examples of likely STATEMENTs include descriptive, control, revision tracking and/or
identifying information.
Figure 2 overleaf shows this relationship. The shaded boxes are subject of this specification while the bold
boxes are defined in ISO/IEC 21000-2.
Several elements within a Digital Item Declaration can have zero, one or more DESCRIPTORs (as specified in
ISO/IEC 21000-2). Each DESCRIPTOR may contain one STATEMENT which can contain one identifier relating to
the parent element of the STATEMENT. In Figure 2, the two statements shown are used to identify a
Component (left hand side of the diagram) and an Item (right hand side of the diagram).

1) As specified in ISO/IEC 13818-3.
2) As specified in ISO 10646.
3) As specified in ISO/IEC 10918.
4) As specified in W3C's HTML 4.0 Specification.
5) As specified in ISO/IEC 21000-2.
2 © ISO/IEC 2003 — All rights reserved

backcover.jpg
MPEG-21
covernotes.html
Music Album
meta-
cover.jpg
data
track1.aac track2.aac track3.aac
meta- meta- meta-
data data data
Identifiers:
lyrics1.aac lyrics2.aac
- IRSC
meta- meta-
- ISMN
data data
Descripions:
- Title
- Composer
- Lyricist
- Duration
- Singer
Figure 1 — MPEG-21 Music Album

Item Descriptor
Item Descriptor Item
Component Descriptor
Descriptor
Item Descriptor Item Descriptor
Descriptor
Component Descriptor
Descriptor
Statement Statement


myID:1234 ID_Scheme:ABCD


Figure 2 — Relationship between Digital Item Declaration and Digital Item Identification
© ISO/IEC 2003 — All rights reserved 3

Figure 3 below gives an example of a DID Descriptor containing one identifier. Please note the use of the DII
Schema (identified by the DII namespace) as defined in Clause 4.4.

xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS">





urn:mpegRA:mpeg21:dii:cid:1702.F109%2F0000011





Figure 3 — Example: Uniquely Identifying a Digital Item
1.5 Using Identifiers to Link Identifiers with Associated Information
Users may link Identifiers to related entities (e.g. related metadata, related Digital Items and parts thereof, etc).
One mechanism for achieving this is by using an online Resolution service such as the Domain Name System
6)
(DNS) Resolution system .
While some of the identification systems that are used to uniquely identify "content" have the capabilities to
resolve an identifier on-line to appropriate metadata (e.g. cIDf, DOI), others do not have this capability (e.g.
ISBN, ISRC). The latter identification systems still enable Users to link the identifier to appropriate metadata
off line. ISO/IEC 21000-2 does not mandate or specify such linking mechanism. Annex A provides an example
of how such linking can be done on line.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC TR 21000-1:2001, Information technology — Multimedia framework (MPEG-21) — Part 1: Vision,
Technologies and Strategy
ISO/IEC 21000-2:2002, Information technology — Multimedia framework (MPEG-21) — Part 2: Digital Item
Declaration
IETF RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax, 1988
IETF RFC 2141, URN Syntax, 1997
IETF RFC 1738, Uniform Resource Locators (URL), 1994
W3C XML Schema — Part 1: Structures, 2001
W3C XML Schema — Part 2: Datatypes, 2001

6) As specified in IETF's RFC 1738.
4 © ISO/IEC 2003 — All rights reserved

3 Terms and definitions
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
Component
A component is the binding of a resource to a set of descriptors. These descriptors are information related to
all or part of the specific resource instance. Such descriptors will typically contain control or structural
information about the resource (such as bit rate, character set, start points or encryption information) but not
information describing the “content” within. It should be noted that a component itself is not an item;
components are building blocks of items. (From ISO/IEC 21000-2)
3.1.2
Descriptor
A descriptor associates information with the enclosing element. This information may be a component (such
as a thumbnail of an image, or a text component), or a textual statement. (From ISO/IEC 21000-2)
3.1.3
Digital item
Structured digital objects, including a standard representation and identification, and meta-data. This entity is
the fundamental unit of distribution and transaction within the MPEG-21 framework as a whole. (From
ISO/IEC 21000-1)
3.1.4
Electronic Media
A means of representing a digital Media Resource in a given media format for electronic distribution.
3.1.5
Entity
Anything that can be uniquely identified (e.g. digital Resources, individuals and organisations, transactions,
etc).
3.1.6
Identification Scheme
A system for associating Identifiers with Entities (both as defined herein), e.g. ISRC, ISBN, etc.
3.1.7
Identifier
A unique label (a string whose function is to distinguish one entity from another) allocated to an entity within a
given namespace, e.g. "ISRC GB-XYZ-01-00001", i.e., the label associated with a specific entity.
3.1.8
Item
An item is a grouping of sub-items and/or components that are bound to relevant descriptors, as defined
within ISO/IEC 21000-2. The term item is a technical term, and is, as such, a narrower term than Digital Item.
3.1.9
Media Resource
Content directly capable of digital representation.
3.1.10
Physical Media
A means of representing either an analogue or a digital Media Resource in a given media format for physical
distribution.
© ISO/IEC 2003 — All rights reserved 5

3.1.11
Resolution
The act of submitting an identifier to a network service and receiving in return one or more pieces of some
information (which includes resources, descriptions, another identifier, Digital Item, etc.) related to the
identifier.
3.1.12
Resource
A resource is an individually identifiable asset such as a video or audio clip, an image, or a textual asset. A
resource may also potentially be a physical object. All resources must be locatable via an unambiguous
address. (From ISO/IEC 21000-2)
3.1.13
Statement
A statement is a literal textual value that contains information, but not an asset. Examples of likely statements
include descriptive, control, revision tracking or identifying information (such as an identifier as described in
any other normative part of ISO/IEC 21000). (From ISO/IEC 21000-2)
3.2 Abbreviations
For the purposes of this part of ISO/IEC 21000, the following abbreviations apply.
cIDf
Content ID Forum
CIS
Common Information System
CISAC
Confédération Internationale des Sociétés d'Auteurs et Compositeurs (International Confederation of
Societies of Authors and Composers)
DCMI
Dublin Core Metadata Initiative
DID
Digital Item Declaration
DII
Digital Item Identification
DOI
Digital Object Identifier
EAN
European Article Number
IEC
International Electrotechnical Commission
ISAN
International Standard Audiovisual Number
ISBN
International Standard Book Number
ISO
International Organization for Standardization
6 © ISO/IEC 2003 — All rights reserved

ISRC
International Standard Recording Code
ISSN
International Standard Serial Number
ISTC
International Standard Textual Work Code
ISWC
International Standard Musical Work Code
MPEG
Moving Picture Expert Group
SMPTE
Society of Motion Picture and Television Engineers
UCC
Uniform Code Council
UPC
Universal Product Code
URI
Uniform Resource Identifier
URL
Uniform Resource Locator
URN
Uniform Resource Name
V-ISAN
Version Identifier for ISAN
4 Identification of Digital Items and their Parts
4.1 Identifier Element
Digital Items and their parts within the MPEG-21 Multimedia Framework are identified by encapsulating
7)
Uniform Resource Identifiers (URIs) into the Identifier element.
4.1.1 Syntax
<--! #############################
ISO/IEC 21000-3 DI Identification Element
#############################>


7) As specified in IETF's RFC 2396.
© ISO/IEC 2003 — All rights reserved 7

4.1.2 Semantics
This element contains an identifier for a Digital Item, container, component, and/or fragment thereof in the
form of a URI.
A Registration Authority is set up for maintaining a list of identification schemes to be used within
ISO/IEC 21000-3. Requirements for the Registration Authority can be found in Annex A.
Identifiers are not required to be registered with the Registration Authority to be conformant to Clause 4.1 of
this specification.
4.1.3 Notes (informative)
A Uniform Resource Identifier (URI) is a compact string of characters for identifying an abstract or physical
resource, where a resource is defined as “anything that has identity”.
The requirement that a Digital Item Identifier be a URI is also consistent with the statement that the MPEG-21
identifier may be a Uniform Resource Locator (URL), since the specification of URI is designed to meet the
8)
recommendations laid out in URL specification . The term URL refers to a specific subset of URI that is in use
today as pointers to information on the Internet; it allows for long-term to short-term persistence depending on
the business case.
4.2 RelatedIdentifier Element
While the Digital Item Identifier element is intended to enable the unique identification of Digital Items (or
parts thereof), the RelatedIdentifier element allows the identification information that is related to the
Digital Item (or parts thereof).
One example for this is the identification of an abstraction of the work (e.g. a composition as an abstraction of
a sound recording).
4.2.1 Syntax
<--! ################################
ISO/IEC 21000-3 DI Related Identifier Element
################################>



4.2.2 Semantics
This element allows associating identifiers that are related to the Digital Item, container, component, and/or
fragment thereof but do not identify the Digital Item (or part thereof) directly. The identifier shall be in the form
of a URI.
The RelatedIdentifier element may not be used for identifying the Digital Item (or part thereof) itself.
This shall be done using the Digital Item Identifier element as specified above.
A Registration Authority is set up for maintaining a list of identification schemes to be used within
ISO/IEC 21000-3. Requirements for the Registration Authority can be found in Annex A.
Identifiers are not required to be registered with the Registration Authority to be conformant to Clause 4.2 of
this specification.
8) As specified in IETF's RFC 1738.
8 © ISO/IEC 2003 — All rights reserved

4.2.3 Example
See Figure 7 for a specific example for the RelatedIdentifier element.
4.3 Type Element
4.3.1 Syntax
<--! ################################
ISO/IEC 21000-3 Type Element
################################>



The Type element shall only appear as the sole child element of a Statement that shall appear as a child
element of a Descriptor that shall appear as a child element of an Item.
4.3.2 Semantics
The Type element will allow subsequent parts of ISO/IEC 21000 to identify special types of Digital Items.
4.3.3 Example
See Figure 8 or a specific example for the Type element.
4.4 Digital Item Identification XML Schema Definition
This clause defines the schema definition for ISO/IEC 21000-3.







xmlns="urn:mpeg:mpeg21:2002:01-DII-NS"
targetNamespace="urn:mpeg:mpeg21:2002:01-DII-NS"
version="0.01">












© ISO/IEC 2003 — All rights reserved 9

ISO/IEC 21000-3 used its own namespace urn:mpeg:mpeg21:2002:01-DII-NS. The “01” represents a
serial number that is expected to change as the schema evolves along with the rest of ISO/IEC 21000. The
"2002" in the namespace identifier is not expected to change when subsequent versions of the
ISO/IEC 21000-2 schema are developed.
4.5 Examples (informative)
The following examples show how to use the Identifier, RelatedIdentifier and Type elements to
identify Digital Items and parts thereof, how to associate related identifiers with Digital Items and how to
identify special Digital Item types.
The second and the third examples also illustrate how to use such identifiers to reference Resources.
4.5.1 Example: Identification of a Music Release
This example shows how to use the Identifier element to uniquely identify a Digital Item containing a
music release. The identifier used stems from a proprietary identification scheme using the namespace myID.
Please note that myID is not a registered URN namespace.


xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS"
xmlns:release="urn:release:2002:01-RELEASE-NS">



Impossible Super Singles 2001





myID:A1-888999-0029733-22-F





Super Singles '01
Super Singles 2001





Figure 4 — Example: Identification of a Musical Release

4.5.2 Example: Referring to Digital Item in external DID Document
Digital Item Identifiers can be used to refer to Digital Item, container, component, fragment thereof, or DID
documents that are externally defined. This is an example to show how Digital Item Identifiers can be used for
these purposes. In this example, it is assumed that the Registration Authority for Digital Item Identification
Systems described in Annex A uses the form urn:mpegRA:mpeg21:dii:sss:nnn, where the string sss
denotes the Identifier for an Identification System and nnn denotes a unique identifier within that Identification
System.
10 © ISO/IEC 2003 — All rights reserved

- - - - - - - - - - - - - -.-
(File a) Main DID document including references to an external Digital Item and an external DID
documdent.
- - - - - - - - - - - - - -.-

xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS">





Track 1: Our Youthful Days (Moon Records)







Track 2: Tomoshibi (GME)








- - - - - - - - - - - - - - - - - - - - - - -
(File b) A DID document “SampleTrack1” located on the server “www.cidf.org” .
- - - - - - - - - - - - - - - - - - - - - - -


xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS">





urn:mpegRA:mpeg21:dii:cid:1702.F109%2F0000011







- - - - - - - - - - - - - - - - - - - - - - -
(File c) A DID document “SampleTrack2” located on the server “www.doi.org”.
- - - - - - - - - - - - - - - - - - - - - - -


xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS">







Figure 5 — Example: Referring to Digital Item in external DID Document
© ISO/IEC 2003 — All rights reserved 11

4.5.3 Example: Referring to Resources stored on external server
Digital Item Identifiers can also be used to refer to Media Resources stored on external servers. In this case,
the association of Identifier with Media Resources are not explicitly declared in DID as in Figure 5 but made by
external identifier providers. Identifiers in this example work just like URLs. Note that the same assumption is
used as Figure 5 for the URN form.

xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS">





Our Youthful Days (MIDI)






Comment of this music





Figure 6 — Example: Referring to Resources stored on external server
4.5.4 Example: Identifying a Sound Recording and the related Underlying Musical Work
This example shows how to uniquely identify a resource (an MPEG Audio Layer III-coded sound recording)
within a Digital Item using an International Standard Recording Code (ISRC).
This example also highlights how to associate a related identifier (here: identifying the underlying music work
with an International Standard Work Code (ISWC)) with such a resource.

xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS">





urn:mpegRA:mpeg21:dii:isrc:US-ZO3-99-32476





urn:mpegRA:mpeg21:dii:iswc:T-034.524.680-1







Figure 7 — Example: Identifying a Sound Recording and the related Underlying Musical Work
12 © ISO/IEC 2003 — All rights reserved

4.5.5 Example: Identifying a Digital Item Type
This example shows how to identify a special Digital Item Type “Foo Digital Item”, which is assumed for this
example to have been specified in one of the parts of ISO/IEC 21000.
A terminal receiving this Digital Item will therefore be able to detect that it is a Foo Digital Item and act
accordingly.

xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS"




Foo Digital Item




...



Figure 8 — Example: Identifying a Digital Item Type
5 Identification of Description Schemes
9)
The XML Schema definition specifies how to use XML-based Description Schemes within Digital Items by
identifying them through their XML namespace identifier.
ISO/IEC 21000-2 allows to include non-XML-based descriptors into Digital Items by identifying the description
scheme through a unique namespace identifier (i.e. a URI).
Example 3 (Clause 9.3) of ISO/IEC 21000-2 gives an example of how to identify description schemes and to
include metadata from such identification schemes into a Digital Item.

9) As defined in W3C. XML Schema – Part 1: Structures.
© ISO/IEC 2003 — All rights reserved 13

Annex A
(normative)
Requirements for the Registration Authority for Digital Item Identification
Systems
A.1 Identifications Systems to be registered for use within ISO/IEC 21000
Many identifiers will have the form of a URN. Whilst many existing identification systems use their own URN
namespace (e.g. the International Standard Book Number with urn:isbn), not all systems do so. In order to
allow such systems to easily obtain URN conformant identifiers to be used within ISO/IEC 21000, a
Registration Authority is needed.
The Registration Authority will, under its own URN namespace, be able to register identification schemes. This
helps users of the ISO/IEC 21000 to identify different Identification Schemes for use within the ISO/IEC 21000.
For example, the form of urn:mpegRA:mpeg21:dii:cid:1702.F109%2F0000011 can be used for Digital
Item Identifiers when an Identification Scheme “cid” is registered to this Registration Authority by an identifier
provider (here: the cIDf). Note that the first part of the string “urn:mpegRA” is the registered URN namespace
of this Registration Authority, the next part “mpeg21:dii” is defined by this Registration Authority for the
purpose of classification of URIs under their auspices, the string “cid” is assigned to the particular
Identification Scheme by the Registration Authority, and the last part, “1702.F109%2F0000011” is a content
identifier issued by the cIDf. It should be noted t
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