XLIFF Format

The XML Localisation Interchange File Format (or XLIFF) is an OASIS-blessed standard format for translations.

In a nutshell an XLIFF document contains one or more <file> elements. Each file element usually corresponds to a source (file or database table) and contains the source of the localizable data. Once translated, the corresponding localized data for one, and only one, locale is added.

Localizable data are stored in <trans-unit> elements. The <trans-unit> contains a <source> element to store the source text and a (non-mandatory) <target> element to store the translated text.

Note that having several <file> elements in the same XLIFF document is not supported by the TYPO3 CMS Core.

Keep in mind that the default language is always considered to be english, even when you have changed your typo3 backend to another language, so source-language must always be source-language="en".

Basics

Here is a sample XLIFF file:

<?xml version="1.0" encoding="UTF-8"?>
<xliff version="1.0" xmlns="urn:oasis:names:tc:xliff:document:1.1">
   <file source-language="en" datatype="plaintext" original="EXT:my_ext/Resources/Private/Language/Modules/<ffile-name>.xlf" date="2011-10-18T18:20:51Z" product-name="my_ext">
      <header/>
      <body>
         <trans-unit id="headerComment" resname="headerComment">
            <source>The default Header Comment.</source>
         </trans-unit>
         <trans-unit id="generator" resname="generator">
            <source>The "Generator" Meta Tag.</source>
         </trans-unit>
      </body>
   </file>
</xliff>

Note

The following properties should be filled properly to get best support in external translation tools:

original
This property contains the path to the xlf file.
resname
Its content is shown to translators. It should be a copy of the property id.

The translated file is very similar. If the original file was named locallang.xlf, the translated file for German (code “de”) will be named de.locallang.xlf. Note that the original file must always be in english, so it is not allowed to create a file with the prefix “en” e.g. en.locallang.xlf. Inside the file itself, a <target-language> attribute is added in the <file> tag to indicate the translation language (“de” in our example). Then for each <source> tag there’s a sibling <target> tag containing the translated string.

Here is what the translation of our sample file could look like:

<xliff version="1.0" xmlns="urn:oasis:names:tc:xliff:document:1.1">
   <file source-language="en" target-language="de" datatype="plaintext" original="EXT:my_ext/Resources/Private/Language/Modules/<ffile-name>.xlf" date="2011-10-18T18:20:51Z" product-name="my_ext">
      <header/>
      <body>
         <trans-unit id="headerComment" resname="headerComment">
            <source>The default Header Comment.</source>
            <target>Der Standard-Header-Kommentar.</target>
         </trans-unit>
         <trans-unit id="generator" resname="generator">
            <source>The "Generator" Meta Tag.</source>
            <target>Der "Generator"-Meta-Tag.</target>
         </trans-unit>
      </body>
   </file>
</xliff>

Only one language can be stored per file and each translation in a different language goes to an additional file.

File Locations and Naming

In the TYPO3 Core, XLIFF files are located in the various system extensions as needed and are expected to be located in Resources/Private/Language.

In Extbase, the main file (locallang.xlf) will be loaded automatically and available in the controller and Fluid views without further work needed. Other files will need to be referred to explicitly using the EXT:LLL:extkey/path/to/file:my.label syntax.

As mentioned above, the translation files follow the same naming conventions, but are prepended with the language code and a dot. They are stored alongside the default language files.

ID Naming

There is no strict rule or guideline in place for defining identifiers (the id attribute). Still it is best practice to follow these rules:

Separate by Dots

Use dots to separate logical parts of the identifier.

Good example:

CType.menu_abstract

Bad examples:

CType_menu_abstract
CType-menu_abstract

Namespace

Group identifiers together with a useful namespace.

Good example:

CType.menu_abstract

This groups all available content types for content elements by using the same prefix CType..

Bad example:

menu_abstract

Namespaces should be defined by context. menu_abstract.CType could also be a reasonable namespace if the context is about menu_abstract.

lowerCamelCase

Generally, lowerCamelCase should be used:

Good example:

frontendUsers.firstName

Exceptions:

  • For some specific cases where the referenced identifier is in a format other than lowerCamelCase, that format can be used: For example, database table or column names often are written in snake_case, and the XLIFF key then might be something like fe_users.first_name.