My name is Tedjuh10, and I'm mainly responsible for the Dutch translations at Wikia (prior to translatewiki.net). Now there is a problem. All extensions in Dutch and Dutch help/information pages at Wikia are informal Dutch ("je/jij/jouw") while all translations done at translatewiki are formal Dutch ("u/uw"). My question is if a new languagecode can be created, just like German (du-formal), called NL-informal. I guess we can just import all extension translations from Wikia to translatewiki, as they are all informal.
This also provides new wiki creators or other users of projects to choose a formal or informal form.
Added code 'nl-informal'. Please only fill the code with those messages that require an informal version; doing 'everything' would just be unnecessary effort. Best start with MediaWiki core, and only then with Wikia extensions. Take your time; quality is important.