The number of languages supported by the standard CJuiDatePicker implementation is limited and the language code to use is different from the application's language code.
This Wiki shows how to improve on that.
Sometimes you want to use exisiting translations for locales, which do not directly match.
An example would be a website targeting Germany (de_de), Austria (de_at) and Switzerland (de_ch, fr_ch, it_ch). Although you may have
exisiting translations for German (de), French (fr) and Italian (it), there are problems using it directly.