This XML format is used for "locallang-XML" (llXML) files, a format TYPO3 uses for storage of interface labels and translations of them. The format is parsed by t3lib_div::xml2array() which means that tag- names and "index" attribute values are inter-related in significance. The content is always in utf-8.

llXML files must be used from inside extension directories (system/global/local).

See Inside TYPO3 for more details about these files and the application of this format.

llXML files from installed extensions can be translated locally by a backend tool (extension "llxmltranslate") and remotely on the TYPO3 translation server.

A "locallang-XML" file contains a set of labels in the default language (must always English!). The translated labels are located in systematically named external files in typo3conf/l10n/[language key]/. Optionally the main files can contain the translations directly but that should only be used in special cases since it constrains the translation process too much. It is also possible with a specific file reference to use other external files than the automated ones.