XML Localization Interchange File Format (XLIFF) is an open XML-based format standard for exchanging localizable data.
Translation content can be stored in an endless number of file formats created for use in many different applications. Some of these formats are highly structured and organized, which makes it easy to export source texts and reimport translations, while others are not. It would be impossible for Computer-Aided Translation (CAT) Tools to support them all. A better approach is to extract text for translation from the source files and save it to an intermediary format optimized for localization. Files in that format can then be imported into CAT tools and used to store the text in both the source and target languages. Once translation is done, they are reintegrated into the original source format to produce localized files in the target language. XLIFF is the most-widely used intermediary format of this kind and can be used by most CAT tools.
XLIFF is often used to exchange data between a client and localization vendor as well as internally between localization software such as CAT tools and Machine Translation systems. The owner of the standard is OASIS XLIFF TC and the latest version is XLIFF 2.0 (2014). The standard consists of a universal core, while more advanced functionality is available through optional modules. XLIFF files are capable of storing the following information:
- text formatting,
- string length restrictions,
- revision history,
- fuzzy matching,
- basic termbase elements,
Virtually all modern localization tools support XLIFF for importing and exporting. However, since it is possible to "extend" the data with custom modules, some file properties and attributes could be lost during transfer between tools.
TMX is another popular standardized file format that is also XML-based. TMX allows any number of languages in the same document, while XLIFF is designed to work with one source and one target language.