Translations:Help:Extension:Translate/Page translation example/33/en

In this example, the whole category assignment is a translation unit. This lets translators change it to or whatever naming convention you want to use for categories. If it were outside the translation template, you would have all the pages Foo, Foo/de, Foo/ru, Foo/ta and so on in the same category. Sometimes this is okay, but usually it distracts the users. Make sure your translators know what the local convention is.