Graphic technology -- Extensible metadata platform (XMP)

This document defines two essential components of XMP metadata: — Data model: The data model is the most fundamental aspect. This is an abstract model that defines the forms of XMP metadata items, essentially the structure of statements that XMP can make about resources. — Serialization: The serialization of XMP defines how any instance of the XMP data model can be recorded as XML. In addition, this document defines a collection of core properties, which are XMP metadata items that can be applied across a broad range of file formats and domains of usage. The embedding of XMP packets in specific file formats and domain-specific XMP properties are beyond the scope of this document.

Technologie graphique -- Spécification de la plate-forme de métadonnées extensibles (XMP)

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Status
Published
Publication Date
25-Apr-2019
Current Stage
6060 - International Standard published
Start Date
06-Apr-2019
Completion Date
26-Apr-2019
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INTERNATIONAL ISO
STANDARD 16684-1
Second edition
2019-04
Graphic technology — Extensible
metadata platform (XMP) —
Part 1:
Data model, serialization and core
properties
Technologie graphique — Spécification de la plate-forme de
métadonnées extensibles (XMP) —
Partie 1: Modèle de données, mise en série et paramètres principaux
Reference number
ISO 16684-1:2019(E)
ISO 2019
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ISO 16684-1:2019(E)
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© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
ii © ISO 2019 – All rights reserved
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ISO 16684-1:2019(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Notations....................................................................................................................................................................................................................... 3

5 Conformance ............................................................................................................................................................................................................. 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Conforming readers ............................................................................................................................................................................ 3

5.3 Conforming writers ............................................................................................................................................................................. 4

5.4 Conforming products ......................................................................................................................................................................... 4

6 Data model .................................................................................................................................................................................................................. 4

6.1 XMP packets .............................................................................................................................................................................................. 4

6.2 XMP names ................................................................................................................................................................................................. 5

6.3 XMP value forms .................................................................................................................................................................................... 6

6.3.1 General...................................................................................................................................................................................... 6

6.3.2 Simple values ...................................................................................................................................................................... 6

6.3.3 Structure values ................................................................................................................................................................ 6

6.3.4 Array values ......................................................................................................................................................................... 7

6.4 Qualifiers ...................................................................................................................................................................................................... 8

7 Serialization .............................................................................................................................................................................................................. 8

7.1 General ........................................................................................................................................................................................................... 8

7.2 Equivalent RDF and XML ................................................................................................................................................................ 9

7.3 Optional outer XML ..........................................................................................................................................................................10

7.3.1 General...................................................................................................................................................................................10

7.3.2 XMP packet wrapper .................................................................................................................................................10

7.3.3 x:xmpmeta element ....................................................................................................................................................11

7.4 rdf:RDF and r df:Description elements ............................................................................................................................11

7.5 Simple valued XMP properties ...............................................................................................................................................12

7.6 Structure valued XMP properties .........................................................................................................................................13

7.7 Array valued XMP properties ..................................................................................................................................................13

7.8 Qualifiers ...................................................................................................................................................................................................14

7.9 Equivalent forms of RDF ..............................................................................................................................................................18

7.9.1 General...................................................................................................................................................................................18

7.9.2 Allowed equivalent RDF .........................................................................................................................................18

7.9.3 Prohibited equivalent RDF ...................................................................................................................................22

8 Core properties ...................................................................................................................................................................................................23

8.1 Overview ...................................................................................................................................................................................................23

8.2 Core value types ..................................................................................................................................................................................23

8.2.1 Basic value types ...........................................................................................................................................................23

8.2.2 Derived value types ....................................................................................................................................................24

8.3 Dublin Core namespace ................................................................................................................................................................27

8.4 XMP namespace ..................................................................................................................................................................................30

8.5 XMP Rights Management namespace ..............................................................................................................................30

8.6 XMP Media Management namespace ...............................................................................................................................31

8.7 xmpidq namespace ...........................................................................................................................................................................32

Annex A (informative) Document and instance IDs ...........................................................................................................................33

Annex B (informative) Implementation guidance ...............................................................................................................................34

Annex C (informative) RDF parsing information ..................................................................................................................................36

© ISO 2019 – All rights reserved iii
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ISO 16684-1:2019(E)

Bibliography .............................................................................................................................................................................................................................49

iv © ISO 2019 – All rights reserved
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ISO 16684-1:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 130, Graphic technology.

This second edition cancels and replaces the first edition (ISO 16684-1:2012), which has been

technically revised.
A list of all parts in the ISO 16684 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
© ISO 2019 – All rights reserved v
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ISO 16684-1:2019(E)
Introduction

This document specifies a standard for the definition, creation, and processing of metadata that can be

applied to a broad range of resource types. The Extensible Metadata Platform (XMP) was introduced

by Adobe Systems Incorporated in 2001 and has since established itself as a critical technology for

improving business efficiency in many industries. The Adobe Systems XMP Specification Part 1

version of July 2010 is the basis for this document. Establishing this document ensures the stability

and longevity of its definitions and encourages broader integration and interoperability of XMP with

existing standards.

Metadata is data that describes the characteristics or properties of a resource. It can be distinguished

from the main content of a resource. For example, for a word processing document, the content includes

the actual text data and formatting information, while the metadata might include properties such as

author, modification date, or copyright status.

Some information could be treated as either content or metadata, depending on context. In general,

metadata is useful without regard for a resource’s content. For example, a list of all fonts used in a

document could be useful metadata, while information about the specific font used for a specific

paragraph on a page would be logically treated as content.

Metadata allows users and applications to work more effectively with resources. Applications can make

use of metadata, even if they cannot understand the native format of the resource’s content. Metadata

can greatly increase the utility of resources in collaborative production workflows. For example, an

image file might contain metadata such as its working title, description, and intellectual property

rights. Accessing the metadata makes it easier to perform such tasks as searching for images, locating

image captions, or determining the copyright clearance to use an image.

File systems have typically provided metadata such as file modification dates and sizes. Other metadata

can be provided by other applications, or by users. Metadata might or might not be stored as part of the

resource with which it is associated.

This document provides a thorough understanding of the XMP data model. It is useful for anyone who

wishes to use XMP metadata, including both developers and end-users of applications that handle

metadata for resources of any kind.

The serialization information is vital for developers of applications that will generate, process, or

manage files containing XMP metadata. The serialization information will also interest application

developers wishing to understand file content. This document also provides additional guidelines for

programmers who will implement XMP metadata processors.

The International Organization for Standardization (ISO) draws attention to the fact that it is claimed

that conformity with this document may involve the use of a patent concerning the creation, processing,

modification, and storage of XMP metadata.

ISO takes no position concerning the evidence, validity and scope of this patent right. The holder of

this patent right has assured ISO that he is willing to negotiate licences under reasonable and non-

discriminatory terms and conditions with applicants throughout the world. In this respect, the

statement of the holder of this patent right is registered with ISO. Information may be obtained from:

Adobe Systems Incorporated 345 Park Avenue
San Jose, California, 95110-2704 USA

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights other than those identified above. ISO shall not be held responsible for identifying any or

all such patent rights.
vi © ISO 2019 – All rights reserved
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INTERNATIONAL STANDARD ISO 16684-1:2019(E)
Graphic technology — Extensible metadata platform
(XMP) —
Part 1:
Data model, serialization and core properties
1 Scope
This document defines two essential components of XMP metadata:

— Data model: The data model is the most fundamental aspect. This is an abstract model that defines

the forms of XMP metadata items, essentially the structure of statements that XMP can make about

resources.

— Serialization: The serialization of XMP defines how any instance of the XMP data model can be

recorded as XML.

In addition, this document defines a collection of core properties, which are XMP metadata items that

can be applied across a broad range of file formats and domains of usage.

The embedding of XMP packets in specific file formats and domain-specific XMP properties are beyond

the scope of this document.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

IEEE 754, Standard for Binary Floating-Point Arithmetic http:/ /grouper. ieee. org/groups/754/

IETF RFC 3066, Tags for the Identification of Languages, January 2001 http://www. ietf. org/rfc/rfc3066.

txt

IETF RFC 3986, Uniform Resource Identifier (URI): Generic Syntax, January 2005 http://www.

ietf .org/rfc/rfc3986 .txt
Set D.C.M.E. Version 1.1, Octor 2010 http:/ /dublincore. org/documents/dces/
The Unicode Standard. http:/ /www. unicode .org/standard/standard. html

URIs. URLs, and URNs: Clarifications and Recommendations 1.0, W3C Note 21 September 2001

http: //www.w3 .org/TR/2001/NOTE-uri -clarification -20010921/
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:—

ISO Online browsing platform: available at https:/ /www. iso. org/obp
— IEC Electropedia: available at http:/ /www.el ectropedia. org/
© ISO 2019 – All rights reserved 1
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ISO 16684-1:2019(E)
3.1
character data
XML text that is not markup
[SOURCE: Extensible Markup Language specification, Section 2.4]
3.2
element content
XML text between the start-tag and end-tag of an element

[SOURCE: : Extensible Markup Language specification, Section 3.1, syntax production 43]

3.3
empty-element tag
XML tag identifying an element with no content
[SOURCE: Extensible Markup Language specification, Section 3.1]
3.4
NCName
XML name that does not contain a colon (‘:’, U+003A)
[SOURCE: Namespaces in XML, Section 3, syntax production 4]
3.5
property
named container for a metadata value at the top level of an XMP packet

Note 1 to entry: Lower-level components of an XMP packet are structure fields, array items, and qualifiers.

3.6
RDF
Resource Description Framework
XML syntax for describing metadata
[SOURCE: RDF/XML Syntax Specification]
3.7
rendition

resource that is a rendering of some other resource in a particular form

Note 1 to entry: Various renditions of a resource have the same content in differing forms. For example, a digital

image could have high resolution, low resolution, or thumbnail renditions. A text document could be in a word

processor format for editing or rendered as a PDF for sharing. See also version (of a resource).

3.8
URI
Uniform Resource Identifier
compact sequence of characters that identifies an abstract or physical resource
[SOURCE: IETF RFC 3986]
3.9
version
resource that is the result of editing some other resource

Note 1 to entry: Different versions of a resource typically have differing content in the same form. See also

rendition (of a resource).
2 © ISO 2019 – All rights reserved
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ISO 16684-1:2019(E)
3.10
XML element
primary component of XML syntax

[SOURCE: Extensible Markup Language specification, Section 3, syntax production 39]

3.11
XML expanded name
pair of strings consisting of a namespace URI and a local name
[SOURCE: Namespaces in XML, Section 2.1]
3.12
XMP processor

hardware or software component that is responsible for reading, modifying, or writing XMP

3.13
white space

XML text consisting of one or more space characters, carriage returns, line feeds, or tabs

[SOURCE: Extensible Markup Language specification, Section 2.3]
4 Notations
The following typeface styles are used for specific types of text:
Table 1 — Conventions for type styles
Typeface style Used for
Bold XMP property names. For example, x mp : C re ate D ate
Italic Terms when defined in text, document titles, or emphasis
The following names are used for important Unicode characters:
— SPACE - U+0020
— QUOTE - U+0022 (")
— APOSTROPHE - U+0027 (')
5 Conformance
5.1 General

Conforming XMP packets shall adhere to all requirements of this document and conforming XMP

packets are not required to use any feature other than those explicitly required by this document.

NOTE The proper mechanism by which XML can presumptively identify itself as being an XMP packet is

described in 7.3, “Optional outer XML”, and 7.4, “rdf: RDF and rdf: Description elements”.

5.2 Conforming readers

A conforming reader shall adhere to all requirements regarding reader functional behaviour specified

in this document. The requirements of this document with respect to reader behaviour are stated in

terms of general functional requirements applicable to all conforming readers. A conforming reader

shall accept all output from conforming writers, including optional output that conforming writers

may produce. This document does not prescribe any specific technical design, user interface, or

implementation details for conforming readers.
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ISO 16684-1:2019(E)
5.3 Conforming writers

A conforming writer shall adhere to all requirements regarding writer functional behaviour specified

in this document. The requirements of this document with respect to writer behaviour are stated in

terms of general functional requirements applicable to all conforming writers and focus on the creation

of conforming XMP packets. This document does not prescribe any specific technical design, user

interface, or implementation details for conforming writers.
5.4 Conforming products

A conforming product shall adhere to all requirements regarding reader and writer functional

behaviour as specified in this document.
6 Data model
6.1 XMP packets

An instance of the XMP data model is called an XMP packet. An XMP packet is a set of XMP metadata

properties. Each property has a name, which is an XML expanded name, and a value. Each such property

name shall be unique within its direct node element, i.e. the highest level r d f : D e s c r ip t ion element to

which it belongs.

NOTE 1 The restriction for unique names means that it is invalid to have multiple occurrences of the same

property name in an XMP packet. Multiple values are represented using an XMP array value (see 6.3.4, “Array

values”). Instead of having three dc : s ubj e c t properties that each hold one keyword, there would be one dc:

subject property that is an array with three items.

All properties in a single XMP packet shall describe a single resource. Separate XMP packets may

describe the same resource. Conflict resolution for separate packets that describe the same resource is

beyond the scope of this document.

Lower-level components of an XMP packet (structure fields or array items) may describe one or more

other resources.

NOTE 2 The provision for lower-level components about some other resource is not an addition to the data

model, in that this is not a formal feature of the data model and is not reflected in written XMP in any specific

manner. Rather, it is a clarification to the “one packet about one resource” rule, to avoid disallowing certain data

models. The XMP about a compound resource might have a list of constituent resources and even copies of XMP

about those constituents. This would all be modelled using the defined XMP value forms.

The composition of a resource and the precise association of an XMP packet with a resource is beyond

the scope of this document. Where feasible, an XMP packet should be physically associated with the

resource that it describes.

NOTE 3 A common resource is a complete digital file, or an identifiable part of a digital file such as an embedded

image in PDF. The structure of a PDF file and the manner of associating XMP with any particular component of a

PDF file is beyond the scope of this document.

The XMP packet that describes a digital file or part of a digital file should be embedded in the file

using standard features of the file format to provide the association between the XMP packet and the

resource. The embedding mechanisms for specific file formats are beyond the scope of this document.

An XMP packet may contain a URI, called the AboutURI, that identifies the resource that the packet

describes. The URI scheme, detailed URI syntax, and association of the URI with any target entity is

beyond the scope of this document.

NOTE 4 It is possible for an XMP packet to not contain an AboutURI and not have a physical association with

the resource. Instead, there can be an external means of association.
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ISO 16684-1:2019(E)

EXAMPLE Consider the statement, “The author of Moby Dick is Herman Melville”. This statement is

represented by metadata in which the resource is the book “Moby Dick”, the property name is “author”, and the

property value is “Herman Melville”, as in Figure 1. (This is only a diagram, not an example of well-formed XMP.).

Figure 1 — Simple properties example diagram

NOTE 5 Notation such as that in Figure 1 is used in this document to illustrate the XMP data model.

An XMP processor should accept all well-formed XMP as input, regardless of the data model expressed,

and should by default preserve all unanticipated XMP when modifying a resource.

NOTE 6 The intent of these rules is that XMP is generally open to arbitrary extension of properties. Users of

XMP are allowed to freely invent custom metadata and to expect XMP-aware applications to support the creation,

modification, and viewing of that metadata. Therefore, this is expressed as a recommendation instead of as a

requirement because any particular environment could have local policies about XMP usage.

6.2 XMP names

Properties (6.1, “XMP packets”) have names, as do fields of structure values (6.3.3, “Structure values”)

and qualifiers (6.4, “Qualifiers”). All names in XMP shall be XML expanded names, consisting of a

namespace URI and a local name. The namespace URI for an XMP name shall not be empty. Two XMP

names shall be equivalent if their namespace URIs are identical and their local names are identical.

This comparison shall be physical, byte-for-byte equality using the same Unicode encoding. Other

processing, including but not limited to Unicode character normalizations, shall not be applied.

NOTE 1 XML namespace URIs are generally best viewed as string literals. Although many XML namespace

URIs begin with “http://" there is no recommendation or requirement that the URI points to a web resource.

The namespace prefix used in XML — and, as a consequence, in XMP — serves only as a key to look up

the appropriate URI. For convenience in this document, XMP names are commonly written in a prefix:

local style, for example, dc: t it le. The relevant URI for the prefix used in this document is either explicit,

clear from local context, or irrelevant (as in the generic value-form diagrams where the specific URI

does not matter).

NOTE 2 The specific convenience is that dc : t i t le is more concise and readable than something like ("http:

//purl .org/dc/elements/1 .1/", creator) in the cases where the namespace URI is known and meaningful. This is

especially so when the precise URI is not relevant, as in an artificial example.
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