Our core systems support 6 languages by default, we use the ISO-639-1 format:
Some languages may have to be activated for you by our support team.
<input type="hidden" name="lang" value="nl">
Other languages not listed here like Chinese may be supported depending on your system. If it is supported for you system, you can use that language. Not supported languages will be redirected to English by default. Example:
<input type="hidden" name="lang" value="zh">