National foreword

This British Standard is the UK implementation of ISO 21720:2024. It supersedes BS ISO 21720:2017, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee TS/1, Terminology.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

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 document should be noted (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

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 OASIS (as XLIFF Version 2.1, February 2018) and drafted in accordance with its editorial rules. It was assigned to Technical Committee ISO/TC 37, Language and terminology, Subcommittee SC 5, Translation, interpreting and related technology, and adopted under the “fast-track procedure”.

This second edition cancels and replaces the first edition (ISO 21720:2017), which has been technically revised.

The main changes are as follows (see also Appendix C):

Two major features are being added in XLIFF Version 2.1:
- Advanced Validation methods;
- Native Support for ITS 2.0.
The Change Tracking Module was demoted to an extension to free hands of the TC and other implementers while working on a new version of the Change Tracking Module for XLIFF 2.2.
A major bug fix was performed on the core xsd. The core xsd now enforces the xs:language data type on the srcLang and trgLang attributes. It was critical to make this fix, because -- as per OASIS policy -- validation artifacts would prevail over the prose provisions that are correct in both XLIFF 2.1 and XLIFF 2.0.
Also an erroneously omitted Constraint of the xml:lang attribute on the <source> element has been added/restored in the normative text.
Apart from the five (5) major changes mentioned above, numerous editorial bugfixes were made to secure greater clarity, either by fixing example errors or omissions, or by reorganizing normative content, so that the intent becomes clear and unequivocal at some troublesome places highlighted by XLIFF 2.0 implementers.
Importantly, the TC decided to drop informative listings of the validation artifacts that had bloated the spec extent unnecessarily, were hard to keep in sync with the actual normative artifacts, while their actual usability proved rather limited -- readers who were able to read schema languages would not actually read them as printed listings and would anyways refer to the actual validation artifacts that are now referenced more prominently.

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.

1 Introduction

XLIFF is the XML Localization 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 nonnormative:

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, tree diagrams, but also any inline examples or illustrative exemplary lists in otherwise normative text),

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

1.0 IPR Policy

This specification is provided under the RF on RAND Terms Mode of the OASIS IPR Policy, the mode chosen when the Technical Committee was established. 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 (https://www.oasis-open.org/committees/xliff/ipr.php).

1.1 Terminology

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

4.3 Attributes

4.4 CDATA sections

4.5 XML Comments

4.6 XML Processing Instructions

4.7 Inline Content

4.8 Segmentation

4.9 Extension Mechanisms

5 The Modules Specifications

5.1 Translation Candidates Module

5.2 Glossary Module

5.3 Format Style Module

5.4 Metadata Module

5.5 Resource Data Module

5.6 Change Tracking Extension (Informative)

5.7 Size and Length Restriction Module

5.8 Validation Module

5.9 ITS Module

BS ISO 21720:2024

XLIFF (XML Localization Interchange File Format)

Current

Published:

31 Jul 2024