XLIFF (XML Localisation interchange file format)

EN-ISO 21720 defines version 2.0 of the XML Localisation Interchange File Format (XLIFF). The purpose of this vocabulary is to store localizable data and carry it from one step of the localization process to the other, while allowing interoperability between and among tools.

XLIFF (Format de fichier XML pour l'échange de données de localisation)

XLIFF (format XML datoteke za izmenjavo lokalizacije)

EN-ISO 21720 opredeljuje različico 2.0 formata XML datoteke za izmenjavo lokalizacije (XLIFF). Namen tega slovarja je shraniti podatke, ki jih je mogoče lokalizirati, in jih prenesti iz enega koraka postopka lokalizacije v drugega, hkrati pa omogočiti interoperabilnost med orodji.

General Information

Status
Published
Public Enquiry End Date
29-Nov-2016
Publication Date
23-Aug-2018
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
30-Jul-2018
Due Date
04-Oct-2018
Completion Date
24-Aug-2018

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INTERNATIONAL ISO
STANDARD 21720
First edition
2017-11
XLIFF (XML Localisation interchange
file format)
XLIFF (Format de fichier XML pour l'échange de données de
localisation)
Reference number
ISO 21720:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 21720:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

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ii © ISO 2017 – All rights reserved
---------------------- Page: 2 ----------------------
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

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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 on 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 the

following URL: www.iso.org/iso/foreword.html.

This document was prepared by OASIS (as XLIFF Version 2.0, August 2014) and was adopted,

under a special “fast‐track procedure”, by Technical Committee ISO/TC 37, Terminology and

other language and content resources, Subcommittee SC 5, Translation, interpreting and related

technology.

iii

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ISO 21720:2017(E)
XLIFF Version 2.0
OASIS Standard
05 August 2014
Specification URIs
This version:

http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.html (Authoritative)

http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.pdf
http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.xml
Previous version:

http://docs.oasis-open.org/xliff/xliff-core/v2.0/cos01/xliff-core-v2.0-cos01.html (Authoritative)

http://docs.oasis-open.org/xliff/xliff-core/v2.0/cos01/xliff-core-v2.0-cos01.pdf
http://docs.oasis-open.org/xliff/xliff-core/v2.0/cos01/xliff-core-v2.0-cos01.xml
Latest version:

http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.html (Authoritative)

http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.pdf
http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.xml
Technical Committee:
OASIS XML Localisation Interchange File Format (XLIFF) TC
Chair:
Bryan Schnabel (bryan.s.schnabel@tektronix.com), Individual
Editors:
Tom Comerford (tom@supratext.com), Individual
David Filip (davidf@ul.ie), Localisation Research Centre
Rodolfo M. Raya (rmraya@maxprograms.com), Maxprograms
Yves Savourel (ysavourel@enlaso.com), ENLASO Corporation
Additional artifacts:
This prose specification is one component of a Work Product that also includes:

XML schemas accessible from http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/schemas/

Related Work:
This specification replaces or supersedes:
XLIFF Version 1.2. 1 February 2008. OASIS Standard. http://docs.oasis-
open.org/xliff/v1.2/os/xliff-core.html
Declared XML Namespaces:
urn:oasis:names:tc:xliff:document:2.0
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ISO 21720:2017(E)
 urn:oasis:names:tc:xliff:matches:2.0
 urn:oasis:names:tc:xliff:glossary:2.0
 urn:oasis:names:tc:xliff:fs:2.0
 urn:oasis:names:tc:xliff:metadata:2.0
 urn:oasis:names:tc:xliff:resourcedata:2.0
 urn:oasis:names:tc:xliff:changetracking:2.0
 urn:oasis:names:tc:xliff:sizerestriction:2.0
 urn:oasis:names:tc:xliff:validation:2.0
Abstract:

This document defines version 2.0 of the XML Localisation Interchange File Format (XLIFF). The

purpose of this vocabulary is to store localizable data and carry it from one step of the localization

process to the other, while allowing interoperability between and among tools.
Status:

This document was last revised or approved by the membership of OASIS on the above date. The

level of approval is also listed above. Check the “Latest version” location noted above for possible

later revisions of this document.

Technical Committee members should send comments on this specification to the Technical

Committee's email list. Others should send comments to the Technical Committee by using the "Send

A Comment" button on the Technical Committee's web page at http://www.oasis-
open.org/committees/xliff/.

For information on whether any patents have been disclosed that may be essential to implementing

this specification, and any offers of patent licensing terms, please refer to the Intellectual Property

Rights section of the Technical Committee web page (http://www.oasis-
open.org/committees/xliff/ipr.php).
Citation format:

When referencing this specification the following citation format should be used:

[XLIFF-2.0]

XLIFF Version 2.0. Edited by Tom Comerford, David Filip, Rodolfo M. Raya, and Yves Savourel. 05

August 2014. OASIS Standard. http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.html.

Latest version: http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.html.

Notices
Copyright © OASIS Open 2014. All Rights Reserved.

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section are included on all such copies and derivative works. However, this document itself may not be

modified in any way, including by removing the copyright notice or references to OASIS, except as needed for

© ISO 2017 – All rights reserved
---------------------- Page: 5 ----------------------
ISO 21720:2017(E)

the purpose of developing any document or deliverable produced by an OASIS Technical Committee (in which

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© ISO 2017 – All rights reserved
iii
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ISO 21720:2017(E)
Table of Contents
1 Introduction
1.1 Terminology
1.1.1 Key words
1.1.2 Definitions
1.1.3 Key concepts
1.2 Normative References
1.3 Non-Normative References
2 Conformance
3 Fragment Identification
3.1 Selectors for Core Elements
3.2 Selectors for Modules and Extensions
3.3 Relative References
3.4 Examples
4 The Core Specification
4.1 General Processing Requirements
4.2 Elements
4.2.1 Tree Structure
4.2.2 Structural Elements
4.2.3 Inline Elements
4.3 Attributes
4.3.1 XLIFF Attributes
4.3.2 XML namespace
4.4 CDATA sections
4.5 XML Comments
4.6 XML Processing Instructions
4.7 Inline Content
4.7.1 Text
4.7.2 Inline Codes
4.7.3 Annotations
4.7.4 Sub-Flows
4.7.5 White Spaces
4.7.6 Bidirectional Text
4.7.7 Target Content Modification
4.7.8 Content Comparison
4.8 Segmentation
4.8.1 Segments Representation
4.8.2 Segments Order
4.8.3 Segmentation Modification
4.9 Extension Mechanisms
4.9.1 Extension Points
4.9.2 Constraints
4.9.3 Processing Requirements
5 The Modules Specifications
5.1 Translation Candidates Module
5.1.1 Introduction
5.1.2 Module Namespace
5.1.3 Module Fragment Identification Prefix
5.1.4 Translation Candidate Annotation
5.1.5 Module Elements
5.1.6 Module Attributes
5.1.7 Example:
5.1.8 XML Schema
5.2 Glossary Module
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ISO 21720:2017(E)
5.2.1 Introduction
5.2.2 Module Namespace
5.2.3 Module Fragment Identification Prefix
5.2.4 Module Elements
5.2.5 Module Attributes
5.2.6 Example:
5.2.7 XML Schema
5.3 Format Style Module
5.3.1 Introduction
5.3.2 Module Namespace
5.3.3 Module Fragment Identification Prefix
5.3.4 Module Specification
5.3.5 Module Attributes
5.3.6 XML Schema
5.4 Metadata Module
5.4.1 Introduction
5.4.2 Module Namespace
5.4.3 Module Fragment Identification Prefix
5.4.4 Module Elements
5.4.5 Module Attributes
5.4.6 XML Schema
5.5 Resource Data Module
5.5.1 Introduction
5.5.2 Module Namespace
5.5.3 Module Fragment Identification Prefix
5.5.4 Module Elements
5.5.5 Module Attributes
5.5.6 Examples:
5.5.7 XML Schema
5.6 Change Tracking Module
5.6.1 Introduction
5.6.2 Module Namespace
5.6.3 Module Fragment Identification Prefix
5.6.4 Module Elements
5.6.5 Module Attributes
5.6.6 Example:
5.6.7 XML Schema
5.7 Size and Length Restriction Module
5.7.1 Introduction
5.7.2 Module Namespace
5.7.3 Module Fragment Identification Prefix
5.7.4 Module Elements
5.7.5 Module Attributes
5.7.6 Standard profiles
5.7.7 Third party profiles
5.7.8 Conformance
5.7.9 Example
5.7.10 XML Schema
5.8 Validation Module
5.8.1 Introduction
5.8.2 Module Namespace
5.8.3 Module Fragment Identification Prefix
5.8.4 Module Elements
5.8.5 Module Attributes
5.8.6 XML Schema
Appendixes
A XML Schemas and Catalog Listings (Informative)
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ISO 21720:2017(E)
A.1 XML Schemas Tree
A.2 XML Catalog
A.3 Core XML Schema
A.4 Support Schemas
B Specification Change Tracking (Informative)
B.1 Tracking of changes made in response to Public Reviews

B.1.1 Tracking of changes in response to the Candidate OASIS Standard Public Review

B.1.2 Tracking of changes in response to the 3rd Public Review
B.1.3 Tracking of changes in response to the 2nd Public Review
B.1.4 Tracking of changes in response to the 1st Public Review
C Acknowledgements (Informative)
© ISO 2017 – All rights reserved
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ISO 21720:2017(E)
1 Introduction

XLIFF is the XML Localisation Interchange File Format designed by a group of multilingual content publishers,

software providers, localization service providers, localization tools providers and researchers. It is intended to

give any multilingual content owner a single interchange file format that can be understood by any localization

provider, using any conformant localization tool. While the primary focus is on being a lossless interchange

format, usage of XLIFF as a processing format is neither encouraged nor discouraged or prohibited.

All text is normative unless otherwise labeled. The following common methods are used for labeling portions

of this specification as informative and hence non-normative:
Appendices and sections marked as "(Informative)" or "Non-Normative" in title,
Notes (sections with the "Note" title),
Warnings (sections with the "Warning" title),

Examples (mainly example code listings but also any inline examples or illustrative exemplary lists in

otherwise normative text),

Schema and other artifacts listings (the corresponding artifacts are normative, not their listings).

1.1 Terminology
1.1.1 Key words
The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT,
RECOMMENDED, MAY, and OPTIONAL are to be interpreted as described in [RFC 2119].
1.1.2 Definitions
Agent

any application or tool that generates (creates), reads, edits, writes, processes, stores, renders or

otherwise handles XLIFF Documents.

Agent is the most general application conformance target that subsumes all other specialized user

agents disregarding whether they are defined in this specification or not.
Enrich, Enriching

the process of associating module and extension based metadata and resources with the Extracted

XLIFF payload
Processing Requirements
 Enriching MAY happen at the time of Extraction.
Note
Extractor knowledge of the native format is not assumed while Enriching.
Enricher, Enricher Agent
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ISO 21720:2017(E)
any Agent that performs the Enriching process
Extract, Extraction

the process of encoding localizable content from a native content or User Interface format as XLIFF

payload, so that localizable parts of the content in the source language are available for Translation

into the target language along with the necessary context information
Extractor, Extractor Agent
any Agent that performs the Extraction process
Merge, Merging

the process of importing XLIFF payload back to the originating native format, based on the full

knowledge of the Extraction mechanism, so that the localized content or User Interface strings replace

the source language in the native format
Merger, Merger Agent
an Agent that performs the Merge process
Warning
Unless specified otherwise, any Merger is deemed to have the same knowledge of
the native format as the Extractor throughout the specification.
Mergers independent of Extractors can succeed, but it is out of scope of this

specification to specify interoperability for Merging back without the full Extractor

knowledge of the native format.
Modify, Modification

the process of changing core and module XLIFF structural and inline elements that were previously

created by other Writers
Processing Requirements
 XLIFF elements MAY be Modified and Enriched at the same time.
Note

Extractor or Enricher knowledge of the native format is not assumed while Modifying.

Modifier, Modifier Agent
an Agent that performs the Modification process
Translation, Translate
a rendering of the meaning of the source text, expressed in the target language
Writer, Writer Agent
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ISO 21720:2017(E)

an Agent that creates, generates, or otherwise writes an XLIFF Document for whatever purpose,

including but not limited to Extractor, Modifier, and Enricher Agents.
Note
Since XLIFF is intended as an exchange format rather than a processing format,
many applications will need to generate XLIFF Documents from their internal
processing formats, even in cases when they are processing XLIFF Documents
created by another Extractor.
1.1.3 Key concepts
XLIFF Core

The core of XLIFF 2.0 consists of the minimum set of XML elements and attributes required to (a)

prepare a document that contains text extracted from one or more files for localization, (b) allow it to

be completed with the translation of the extracted text, and (c) allow the generation of Translated

versions of the original document.
The XML namespace that corresponds to the core subset of XLIFF 2.0 is
"urn:oasis:names:tc:xliff:document:2.0".
XLIFF-defined (elements and attributes)

The following is the list of allowed schema URN prefixes for XLIFF-defined elements and attributes:

urn:oasis:names:tc:xliff:

However, the following namespaces are NOT considered XLIFF-defined for the purposes of the

XLIFF 2.0 specification:
urn:oasis:names:tc:xliff:document:1.0
urn:oasis:names:tc:xliff:document:1.1
urn:oasis:names:tc:xliff:document:1.2
Elements and attributes from other namespaces are not XLIFF-defined.
XLIFF Document
Any XML document that declares the namespace

"urn:oasis:names:tc:xliff:document:2.0" as its main namespace, has as the

root element and complies with the XML Schemas and the declared Constraints that are part of this

specification.
XLIFF Module

A module is an OPTIONAL set of XML elements and attributes that stores information about a

process applied to an XLIFF Document and the data incorporated into the document as result of that

process.

Each official module defined for XLIFF 2.0 has its grammar defined in an independent XML Schema

with a separate namespace.
1.2 Normative References
© ISO 2017 – All rights reserved
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ISO 21720:2017(E)

[BCP 47] M. Davis, Tags for Identifying Languages, http://tools.ietf.org/html/bcp47 IETF (Internet Engineering

Task Force).
[HTML5] W3C, HTML5. A vocabulary and associated APIs for HTML and XHTML,
http://www.w3.org/TR/html5/ W3C Candidate Recommendation 17 December 2012.

[NOTE-datetime] M. Wolf, C. Wicksteed, Date and Time Formats, http://www.w3.org/TR/NOTE-datetime

W3C Note, 15th Setember 1997.
[RFC 2119] S. Bradner, Key words for use in RFCs to Indicate Requirement Levels,

http://www.ietf.org/rfc/rfc2119.txt IETF (Internet Engineering Task Force) RFC 2119, March 1997.

[UAX #9] M. Davis, UNICODE BIDIRECTIONAL ALGORITHM, http://www.unicode.org/reports/tr9/ Unicode

Bidirectional Algorithm.

[UAX #15] M. Davis, K. Whistler, UNICODE NORMALIZATION FORMS, http://www.unicode.org/reports/tr15/

Unicode Normalization Forms.

[Unicode] The Unicode Consortium, The Unicode Standard, http://www.unicode.org/versions/latest/ Mountain

View, CA: The Unicode Consortium, 2012.

[XML] W3C, Extensible Markup Language (XML) 1.0, http://www.w3.org/TR/xml/ (Fifth Edition) W3C

Recommendation 26 November 2008.

[XML namespace] W3C, Schema document for namespace http://www.w3.org/XML/1998/namespace

http://www.w3.org/2001/xml.xsd [http://www.w3.org/2009/01/xml.xsd]. at http://docs.oasis-open.org/xliff/xliff-

core/v2.0/os/schemas/informativeCopiesOf3rdPartySchemas/w3c/xml.xsd in this distribution

[XML Schema Datatypes] W3C, XML Schema Part 2: Datatypes, http://www.w3.org/TR/xmlschema-2/

(Second Edition) W3C Recommendation 28 October 2004.
1.3 Non-Normative References

[ITS] MultilingualWeb-LT WG Internationalization Tag Set (ITS) Version 2.0, 29 October 2013,

http://www.w3.org/TR/its20/ W3C Recommendation.
[LDML] Unicode Locale Data Markup Language http://unicode.org/reports/tr35/
[SRX] Segmentation Rules eXchange http://www.gala-global.org/oscarStandards/srx/

[UAX #29] M. Davis, UNICODE TEXT SEGMENTATION, http://www.unicode.org/reports/tr29/ Unicode text

Segmentation.

[XML I18N BP] Best Practices for XML Internationalization, 13 February 2008, http://www.w3.org/TR/xml-

i18n-bp/ W3C Working Group.
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ISO 21720:2017(E)
2 Conformance
1. Document Conformance

a. XLIFF is an XML vocabulary, therefore conformant XLIFF Documents MUST be well formed

and valid [XML] documents.

b. Conformant XLIFF Documents MUST be valid instances of the official Core XML Schema that

is part of this XLIFF specification.

c. As not all aspects of the XLIFF specification can be expressed in terms of XML Schemas,

conformant XLIFF Documents MUST also comply with all relevant elements and attributes

definitions, normative usage descriptions, and Constraints specified in this specification

document.

d. XLIFF Documents MAY contain custom extensions, as defined in the Extension Mechanisms

section.
2. Application Conformance

a. XLIFF Writers MUST create conformant XLIFF Documents to be considered XLIFF compliant.

b. Agents processing conformant XLIFF Documents that contain custom extensions are not

REQUIRED to understand and process non-XLIFF elements or attributes. However,

conformant applications SHOULD preserve existing custom extensions when processing

conformant XLIFF Documents, provided that the elements that contain custom extensions are

not removed according to XLIFF Processing Requirements or the extension's own processing

requirements.

c. All Agents MUST comply with Processing Requirements for otherwise unspecified Agents or

without a specifically set target Agent.

d. Specialized Agents defined in this specification - this is Extractor, Merger, Writer, Modifier,

and Enricher Agents - MUST comply with the Processing Requirements targeting their

specifically defined type of Agent on top of Processing Requirements targeting all Agents as

per point c. above.

e. XLIFF is a format explicitly designed for exchanging data among various Agents. Thus, a

conformant XLIFF application MUST be able to accept XLIFF Documents it had written after

those XLIFF Documents were Modified or Enriched by a different application, provided that:

i. The processed files are conformant XLIFF Documents,
ii. in a state compliant with all relevant Processing Requirements.
3. Backwards Compatibility

a. Conformant applications are NOT REQUIRED to support XLIFF 1.2 or previous Versions.

Note

XLIFF Documents conformant to this specification are not and cannot be conformant to XLIFF

1.2 or earlier versions. If an application needs to support for whatever business reason both

XLIFF 2.0 and XLIFF 1.2, these will need to be supported as separate functionalities.

© ISO 2017 – All rights reserved
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ISO 21720:2017(E)
3 Fragment Identification

Because XLIFF Documents do not follow the usual behavior of XML documents when it comes to element

identifiers, this specification defines how Agents MUST interpret the fragment identifiers in IRIs pointing to

XLIFF Documents.
Note

Note that some identifiers may change during the localization process. For example

elements may be re-grouped or not depending on how tools treat identical original data.

Constraints
 A fragment identifier MUST match the following format:
::= "#" ["/"] { }
::= [ ]
::= NMTOKEN
::= NMTOKEN
::= "="
::= "/"
 There MUST NOT be two identical prefixes in the expression.

 When used, the following selectors MUST be declared in this order: file selector, group selector and

unit selector.

 The selectors for modules or extensions, , or or source inline

elements, target inline elements and have the following constraints:
o Only one of them MAY be used in the expression.
o The one used MUST be the last selector of the expression.
Warning

Please note that due to the above Constraints, referencing fragments using third party

namespaces within Modules or extensions (including but not limited to XLIFF Core or the

Metadata Module) is not possible. This is to restrict the complexity of the fragment

identification mechanism, as it would otherwise have potentially unlimited depth.

3.1 Selectors for Core Elements

 The prefix f indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.

 The prefix g indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.

 The prefix u indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.

 The prefix n indicates a id and the value of that id is unique among all id attribute

values within the immediate enclosing , , or element.

 The prefix d indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.
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ISO 21720:2017(E)

 The prefix t indicates an id for an inline element in the element and the value of that id is

unique within the enclosing element (with the exception of the matching inline elements in the

).

 No prefix indicates an id for a or an or an inline element in the

element and the value of that id is unique within the enclosing element (with the exception of

the matching inline elements in the ).
3.2 Selectors for Modules and Extensions

A selector for a module or an extension uses a registered prefix and the value of that id is unique within the

immediate enclosing , or element.
Constraints

 The prefix of a module or an extension MUST be an NMTOKEN longer than 1 character and MUST

be defined in the module or extension specification.
 The prefix of a module or an extension MUST be registered with the XLIFF TC.

 A given module or extension namespace URI MUST be associated with a single prefix.

 A prefix MAY be associated with more than one namespace URI (to allow for example different

versions of a given module or extension to use the same prefix).

See also the constraints related to how IDs need to be specified in extensions (which applies for modules as

well).
3.3 Relative References

Fragment identifiers that do not start with a character / (U+002F) are relative to their location in the

document, or to the document being processed.

Any unit, group or file selector missing to resolve the relative reference is obtained from the immediate

enclosing unit, group or file elements.
3.4 Examples
Given the following XLIFF document:
srcLang="en" trgLang="fr">


...

SLOVENSKI STANDARD
SIST ISO 21720:2018
01-september-2018
XLIFF (format XML datoteke za izmenjavo lokalizacije)
XLIFF (XML Localisation interchange file format)
XLIFF (Format de fichier XML pour l'échange de données de localisation)
Ta slovenski standard je istoveten z: ISO 21720:2017
ICS:
35.240.30 Uporabniške rešitve IT v IT applications in information,
informatiki, dokumentiranju in documentation and
založništvu publishing
SIST ISO 21720:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 21720:2018
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SIST ISO 21720:2018
INTERNATIONAL ISO
STANDARD 21720
First edition
2017-11
XLIFF (XML Localisation interchange
file format)
XLIFF (Format de fichier XML pour l'échange de données de
localisation)
Reference number
ISO 21720:2017(E)
ISO 2017
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SIST ISO 21720:2018
ISO 21720:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST ISO 21720:2018
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 on 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 the

following URL: www.iso.org/iso/foreword.html.

This document was prepared by OASIS (as XLIFF Version 2.0, August 2014) and was adopted,

under a special “fast‐track procedure”, by Technical Committee ISO/TC 37, Terminology and

other language and content resources, Subcommittee SC 5, Translation, interpreting and related

technology.

iii

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SIST ISO 21720:2018
ISO 21720:2017(E)
XLIFF Version 2.0
OASIS Standard
05 August 2014
Specification URIs
This version:

http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.html (Authoritative)

http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.pdf
http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.xml
Previous version:

http://docs.oasis-open.org/xliff/xliff-core/v2.0/cos01/xliff-core-v2.0-cos01.html (Authoritative)

http://docs.oasis-open.org/xliff/xliff-core/v2.0/cos01/xliff-core-v2.0-cos01.pdf
http://docs.oasis-open.org/xliff/xliff-core/v2.0/cos01/xliff-core-v2.0-cos01.xml
Latest version:

http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.html (Authoritative)

http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.pdf
http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.xml
Technical Committee:
OASIS XML Localisation Interchange File Format (XLIFF) TC
Chair:
Bryan Schnabel (bryan.s.schnabel@tektronix.com), Individual
Editors:
Tom Comerford (tom@supratext.com), Individual
David Filip (davidf@ul.ie), Localisation Research Centre
Rodolfo M. Raya (rmraya@maxprograms.com), Maxprograms
Yves Savourel (ysavourel@enlaso.com), ENLASO Corporation
Additional artifacts:
This prose specification is one component of a Work Product that also includes:

XML schemas accessible from http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/schemas/

Related Work:
This specification replaces or supersedes:
XLIFF Version 1.2. 1 February 2008. OASIS Standard. http://docs.oasis-
open.org/xliff/v1.2/os/xliff-core.html
Declared XML Namespaces:
urn:oasis:names:tc:xliff:document:2.0
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 urn:oasis:names:tc:xliff:matches:2.0
 urn:oasis:names:tc:xliff:glossary:2.0
 urn:oasis:names:tc:xliff:fs:2.0
 urn:oasis:names:tc:xliff:metadata:2.0
 urn:oasis:names:tc:xliff:resourcedata:2.0
 urn:oasis:names:tc:xliff:changetracking:2.0
 urn:oasis:names:tc:xliff:sizerestriction:2.0
 urn:oasis:names:tc:xliff:validation:2.0
Abstract:

This document defines version 2.0 of the XML Localisation Interchange File Format (XLIFF). The

purpose of this vocabulary is to store localizable data and carry it from one step of the localization

process to the other, while allowing interoperability between and among tools.
Status:

This document was last revised or approved by the membership of OASIS on the above date. The

level of approval is also listed above. Check the “Latest version” location noted above for possible

later revisions of this document.

Technical Committee members should send comments on this specification to the Technical

Committee's email list. Others should send comments to the Technical Committee by using the "Send

A Comment" button on the Technical Committee's web page at http://www.oasis-
open.org/committees/xliff/.

For information on whether any patents have been disclosed that may be essential to implementing

this specification, and any offers of patent licensing terms, please refer to the Intellectual Property

Rights section of the Technical Committee web page (http://www.oasis-
open.org/committees/xliff/ipr.php).
Citation format:

When referencing this specification the following citation format should be used:

[XLIFF-2.0]

XLIFF Version 2.0. Edited by Tom Comerford, David Filip, Rodolfo M. Raya, and Yves Savourel. 05

August 2014. OASIS Standard. http://docs.oasis-open.org/xliff/xliff-core/v2.0/os/xliff-core-v2.0-os.html.

Latest version: http://docs.oasis-open.org/xliff/xliff-core/v2.0/xliff-core-v2.0.html.

Notices
Copyright © OASIS Open 2014. All Rights Reserved.

All capitalized terms in the following text have the meanings assigned to them in the OASIS Intellectual

Property Rights Policy (the "OASIS IPR Policy"). The full Policy may be found at the OASIS website.

This document and translations of it may be copied and furnished to others, and derivative works that

comment on or otherwise explain it or assist in its implementation may be prepared, copied, published, and

distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this

section are included on all such copies and derivative works. However, this document itself may not be

modified in any way, including by removing the copyright notice or references to OASIS, except as needed for

© ISO 2017 – All rights reserved
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ISO 21720:2017(E)

the purpose of developing any document or deliverable produced by an OASIS Technical Committee (in which

case the rules applicable to copyrights, as set forth in the OASIS IPR Policy, must be followed) or as required

to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by OASIS or its successors or

assigns.

This document and the information contained herein is provided on an "AS IS" basis and OASIS DISCLAIMS

ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT

THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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necessarily be infringed by implementations of this OASIS Committee Specification or OASIS Standard, to

notify OASIS TC Administrator and provide an indication of its willingness to grant patent licenses to such

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specification.

OASIS invites any party to contact the OASIS TC Administrator if it is aware of a claim of ownership of any

patent claims that would necessarily be infringed by implementations of this specification by a patent holder

that is not willing to provide a license to such patent claims in a manner consistent with the IPR Mode of the

OASIS Technical Committee that produced this specification. OASIS may include such claims on its website,

but disclaims any obligation to do so.

OASIS takes no position regarding the validity or scope of any intellectual property or other rights that might

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the OASIS TC Administrator. OASIS makes no representation that any information or list of intellectual

property rights will at any time be complete, or that any claims in such list are, in fact, Essential Claims.

The name "OASIS" is a trademark of OASIS, the owner and developer of this specification, and should be

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© ISO 2017 – All rights reserved
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Table of Contents
1 Introduction
1.1 Terminology
1.1.1 Key words
1.1.2 Definitions
1.1.3 Key concepts
1.2 Normative References
1.3 Non-Normative References
2 Conformance
3 Fragment Identification
3.1 Selectors for Core Elements
3.2 Selectors for Modules and Extensions
3.3 Relative References
3.4 Examples
4 The Core Specification
4.1 General Processing Requirements
4.2 Elements
4.2.1 Tree Structure
4.2.2 Structural Elements
4.2.3 Inline Elements
4.3 Attributes
4.3.1 XLIFF Attributes
4.3.2 XML namespace
4.4 CDATA sections
4.5 XML Comments
4.6 XML Processing Instructions
4.7 Inline Content
4.7.1 Text
4.7.2 Inline Codes
4.7.3 Annotations
4.7.4 Sub-Flows
4.7.5 White Spaces
4.7.6 Bidirectional Text
4.7.7 Target Content Modification
4.7.8 Content Comparison
4.8 Segmentation
4.8.1 Segments Representation
4.8.2 Segments Order
4.8.3 Segmentation Modification
4.9 Extension Mechanisms
4.9.1 Extension Points
4.9.2 Constraints
4.9.3 Processing Requirements
5 The Modules Specifications
5.1 Translation Candidates Module
5.1.1 Introduction
5.1.2 Module Namespace
5.1.3 Module Fragment Identification Prefix
5.1.4 Translation Candidate Annotation
5.1.5 Module Elements
5.1.6 Module Attributes
5.1.7 Example:
5.1.8 XML Schema
5.2 Glossary Module
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5.2.1 Introduction
5.2.2 Module Namespace
5.2.3 Module Fragment Identification Prefix
5.2.4 Module Elements
5.2.5 Module Attributes
5.2.6 Example:
5.2.7 XML Schema
5.3 Format Style Module
5.3.1 Introduction
5.3.2 Module Namespace
5.3.3 Module Fragment Identification Prefix
5.3.4 Module Specification
5.3.5 Module Attributes
5.3.6 XML Schema
5.4 Metadata Module
5.4.1 Introduction
5.4.2 Module Namespace
5.4.3 Module Fragment Identification Prefix
5.4.4 Module Elements
5.4.5 Module Attributes
5.4.6 XML Schema
5.5 Resource Data Module
5.5.1 Introduction
5.5.2 Module Namespace
5.5.3 Module Fragment Identification Prefix
5.5.4 Module Elements
5.5.5 Module Attributes
5.5.6 Examples:
5.5.7 XML Schema
5.6 Change Tracking Module
5.6.1 Introduction
5.6.2 Module Namespace
5.6.3 Module Fragment Identification Prefix
5.6.4 Module Elements
5.6.5 Module Attributes
5.6.6 Example:
5.6.7 XML Schema
5.7 Size and Length Restriction Module
5.7.1 Introduction
5.7.2 Module Namespace
5.7.3 Module Fragment Identification Prefix
5.7.4 Module Elements
5.7.5 Module Attributes
5.7.6 Standard profiles
5.7.7 Third party profiles
5.7.8 Conformance
5.7.9 Example
5.7.10 XML Schema
5.8 Validation Module
5.8.1 Introduction
5.8.2 Module Namespace
5.8.3 Module Fragment Identification Prefix
5.8.4 Module Elements
5.8.5 Module Attributes
5.8.6 XML Schema
Appendixes
A XML Schemas and Catalog Listings (Informative)
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A.1 XML Schemas Tree
A.2 XML Catalog
A.3 Core XML Schema
A.4 Support Schemas
B Specification Change Tracking (Informative)
B.1 Tracking of changes made in response to Public Reviews

B.1.1 Tracking of changes in response to the Candidate OASIS Standard Public Review

B.1.2 Tracking of changes in response to the 3rd Public Review
B.1.3 Tracking of changes in response to the 2nd Public Review
B.1.4 Tracking of changes in response to the 1st Public Review
C Acknowledgements (Informative)
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1 Introduction

XLIFF is the XML Localisation Interchange File Format designed by a group of multilingual content publishers,

software providers, localization service providers, localization tools providers and researchers. It is intended to

give any multilingual content owner a single interchange file format that can be understood by any localization

provider, using any conformant localization tool. While the primary focus is on being a lossless interchange

format, usage of XLIFF as a processing format is neither encouraged nor discouraged or prohibited.

All text is normative unless otherwise labeled. The following common methods are used for labeling portions

of this specification as informative and hence non-normative:
Appendices and sections marked as "(Informative)" or "Non-Normative" in title,
Notes (sections with the "Note" title),
Warnings (sections with the "Warning" title),

Examples (mainly example code listings but also any inline examples or illustrative exemplary lists in

otherwise normative text),

Schema and other artifacts listings (the corresponding artifacts are normative, not their listings).

1.1 Terminology
1.1.1 Key words
The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT,
RECOMMENDED, MAY, and OPTIONAL are to be interpreted as described in [RFC 2119].
1.1.2 Definitions
Agent

any application or tool that generates (creates), reads, edits, writes, processes, stores, renders or

otherwise handles XLIFF Documents.

Agent is the most general application conformance target that subsumes all other specialized user

agents disregarding whether they are defined in this specification or not.
Enrich, Enriching

the process of associating module and extension based metadata and resources with the Extracted

XLIFF payload
Processing Requirements
 Enriching MAY happen at the time of Extraction.
Note
Extractor knowledge of the native format is not assumed while Enriching.
Enricher, Enricher Agent
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any Agent that performs the Enriching process
Extract, Extraction

the process of encoding localizable content from a native content or User Interface format as XLIFF

payload, so that localizable parts of the content in the source language are available for Translation

into the target language along with the necessary context information
Extractor, Extractor Agent
any Agent that performs the Extraction process
Merge, Merging

the process of importing XLIFF payload back to the originating native format, based on the full

knowledge of the Extraction mechanism, so that the localized content or User Interface strings replace

the source language in the native format
Merger, Merger Agent
an Agent that performs the Merge process
Warning
Unless specified otherwise, any Merger is deemed to have the same knowledge of
the native format as the Extractor throughout the specification.
Mergers independent of Extractors can succeed, but it is out of scope of this

specification to specify interoperability for Merging back without the full Extractor

knowledge of the native format.
Modify, Modification

the process of changing core and module XLIFF structural and inline elements that were previously

created by other Writers
Processing Requirements
 XLIFF elements MAY be Modified and Enriched at the same time.
Note

Extractor or Enricher knowledge of the native format is not assumed while Modifying.

Modifier, Modifier Agent
an Agent that performs the Modification process
Translation, Translate
a rendering of the meaning of the source text, expressed in the target language
Writer, Writer Agent
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an Agent that creates, generates, or otherwise writes an XLIFF Document for whatever purpose,

including but not limited to Extractor, Modifier, and Enricher Agents.
Note
Since XLIFF is intended as an exchange format rather than a processing format,
many applications will need to generate XLIFF Documents from their internal
processing formats, even in cases when they are processing XLIFF Documents
created by another Extractor.
1.1.3 Key concepts
XLIFF Core

The core of XLIFF 2.0 consists of the minimum set of XML elements and attributes required to (a)

prepare a document that contains text extracted from one or more files for localization, (b) allow it to

be completed with the translation of the extracted text, and (c) allow the generation of Translated

versions of the original document.
The XML namespace that corresponds to the core subset of XLIFF 2.0 is
"urn:oasis:names:tc:xliff:document:2.0".
XLIFF-defined (elements and attributes)

The following is the list of allowed schema URN prefixes for XLIFF-defined elements and attributes:

urn:oasis:names:tc:xliff:

However, the following namespaces are NOT considered XLIFF-defined for the purposes of the

XLIFF 2.0 specification:
urn:oasis:names:tc:xliff:document:1.0
urn:oasis:names:tc:xliff:document:1.1
urn:oasis:names:tc:xliff:document:1.2
Elements and attributes from other namespaces are not XLIFF-defined.
XLIFF Document
Any XML document that declares the namespace

"urn:oasis:names:tc:xliff:document:2.0" as its main namespace, has as the

root element and complies with the XML Schemas and the declared Constraints that are part of this

specification.
XLIFF Module

A module is an OPTIONAL set of XML elements and attributes that stores information about a

process applied to an XLIFF Document and the data incorporated into the document as result of that

process.

Each official module defined for XLIFF 2.0 has its grammar defined in an independent XML Schema

with a separate namespace.
1.2 Normative References
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[BCP 47] M. Davis, Tags for Identifying Languages, http://tools.ietf.org/html/bcp47 IETF (Internet Engineering

Task Force).
[HTML5] W3C, HTML5. A vocabulary and associated APIs for HTML and XHTML,
http://www.w3.org/TR/html5/ W3C Candidate Recommendation 17 December 2012.

[NOTE-datetime] M. Wolf, C. Wicksteed, Date and Time Formats, http://www.w3.org/TR/NOTE-datetime

W3C Note, 15th Setember 1997.
[RFC 2119] S. Bradner, Key words for use in RFCs to Indicate Requirement Levels,

http://www.ietf.org/rfc/rfc2119.txt IETF (Internet Engineering Task Force) RFC 2119, March 1997.

[UAX #9] M. Davis, UNICODE BIDIRECTIONAL ALGORITHM, http://www.unicode.org/reports/tr9/ Unicode

Bidirectional Algorithm.

[UAX #15] M. Davis, K. Whistler, UNICODE NORMALIZATION FORMS, http://www.unicode.org/reports/tr15/

Unicode Normalization Forms.

[Unicode] The Unicode Consortium, The Unicode Standard, http://www.unicode.org/versions/latest/ Mountain

View, CA: The Unicode Consortium, 2012.

[XML] W3C, Extensible Markup Language (XML) 1.0, http://www.w3.org/TR/xml/ (Fifth Edition) W3C

Recommendation 26 November 2008.

[XML namespace] W3C, Schema document for namespace http://www.w3.org/XML/1998/namespace

http://www.w3.org/2001/xml.xsd [http://www.w3.org/2009/01/xml.xsd]. at http://docs.oasis-open.org/xliff/xliff-

core/v2.0/os/schemas/informativeCopiesOf3rdPartySchemas/w3c/xml.xsd in this distribution

[XML Schema Datatypes] W3C, XML Schema Part 2: Datatypes, http://www.w3.org/TR/xmlschema-2/

(Second Edition) W3C Recommendation 28 October 2004.
1.3 Non-Normative References

[ITS] MultilingualWeb-LT WG Internationalization Tag Set (ITS) Version 2.0, 29 October 2013,

http://www.w3.org/TR/its20/ W3C Recommendation.
[LDML] Unicode Locale Data Markup Language http://unicode.org/reports/tr35/
[SRX] Segmentation Rules eXchange http://www.gala-global.org/oscarStandards/srx/

[UAX #29] M. Davis, UNICODE TEXT SEGMENTATION, http://www.unicode.org/reports/tr29/ Unicode text

Segmentation.

[XML I18N BP] Best Practices for XML Internationalization, 13 February 2008, http://www.w3.org/TR/xml-

i18n-bp/ W3C Working Group.
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2 Conformance
1. Document Conformance

a. XLIFF is an XML vocabulary, therefore conformant XLIFF Documents MUST be well formed

and valid [XML] documents.

b. Conformant XLIFF Documents MUST be valid instances of the official Core XML Schema that

is part of this XLIFF specification.

c. As not all aspects of the XLIFF specification can be expressed in terms of XML Schemas,

conformant XLIFF Documents MUST also comply with all relevant elements and attributes

definitions, normative usage descriptions, and Constraints specified in this specification

document.

d. XLIFF Documents MAY contain custom extensions, as defined in the Extension Mechanisms

section.
2. Application Conformance

a. XLIFF Writers MUST create conformant XLIFF Documents to be considered XLIFF compliant.

b. Agents processing conformant XLIFF Documents that contain custom extensions are not

REQUIRED to understand and process non-XLIFF elements or attributes. However,

conformant applications SHOULD preserve existing custom extensions when processing

conformant XLIFF Documents, provided that the elements that contain custom extensions are

not removed according to XLIFF Processing Requirements or the extension's own processing

requirements.

c. All Agents MUST comply with Processing Requirements for otherwise unspecified Agents or

without a specifically set target Agent.

d. Specialized Agents defined in this specification - this is Extractor, Merger, Writer, Modifier,

and Enricher Agents - MUST comply with the Processing Requirements targeting their

specifically defined type of Agent on top of Processing Requirements targeting all Agents as

per point c. above.

e. XLIFF is a format explicitly designed for exchanging data among various Agents. Thus, a

conformant XLIFF application MUST be able to accept XLIFF Documents it had written after

those XLIFF Documents were Modified or Enriched by a different application, provided that:

i. The processed files are conformant XLIFF Documents,
ii. in a state compliant with all relevant Processing Requirements.
3. Backwards Compatibility

a. Conformant applications are NOT REQUIRED to support XLIFF 1.2 or previous Versions.

Note

XLIFF Documents conformant to this specification are not and cannot be conformant to XLIFF

1.2 or earlier versions. If an application needs to support for whatever business reason both

XLIFF 2.0 and XLIFF 1.2, these will need to be supported as separate functionalities.

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3 Fragment Identification

Because XLIFF Documents do not follow the usual behavior of XML documents when it comes to element

identifiers, this specification defines how Agents MUST interpret the fragment identifiers in IRIs pointing to

XLIFF Documents.
Note

Note that some identifiers may change during the localization process. For example

elements may be re-grouped or not depending on how tools treat identical original data.

Constraints
 A fragment identifier MUST match the following format:
::= "#" ["/"] { }
::= [ ]
::= NMTOKEN
::= NMTOKEN
::= "="
::= "/"
 There MUST NOT be two identical prefixes in the expression.

 When used, the following selectors MUST be declared in this order: file selector, group selector and

unit selector.

 The selectors for modules or extensions, , or or source inline

elements, target inline elements and have the following constraints:
o Only one of them MAY be used in the expression.
o The one used MUST be the last selector of the expression.
Warning

Please note that due to the above Constraints, referencing fragments using third party

namespaces within Modules or extensions (including but not limited to XLIFF Core or the

Metadata Module) is not possible. This is to restrict the complexity of the fragment

identification mechanism, as it would otherwise have potentially unlimited depth.

3.1 Selectors for Core Elements

 The prefix f indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.

 The prefix g indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.

 The prefix u indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.

 The prefix n indicates a id and the value of that id is unique among all id attribute

values within the immediate enclosing , , or element.

 The prefix d indicates a id and the value of that id is unique among all id attribute

values within the enclosing element.
© ISO 2017 – All rights reserved
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SIST ISO 21720:2018
ISO 21720:2017(E)

 The prefix t indicates an id for an inline element in the element and the value of that id is

unique within the enclosing element (with the exception of the matching inline elements in the

).

 No prefix indicates an id for a or an or an inline element in the

element and the value of that id is unique within the enclosing element (with the exception of

the matching inline elements in the ).
3.2 Selectors for Modules and Extensions

A selector for a module or an extension uses a registered prefix and the value of that id is unique within the

immediate enclosing , ...

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