Proposed policy (in accordance with langcom:Language proposal policy/GerardM-Pathoschild, which seems likely to be accepted).
Incubator is a place for testing new languages of existing projects. Not for testing new projects. (?)
At least 5 active users contributing information (not just wikifying etc.) to the test.
Apply for new language, as described here. Once conditional support given, start test here.
The new test pages will all start with a prefix of the form "project/lang-code/" so, "wp/en/" for english wikipedia or "wn/bvj" for Baan wikibooks. The code should ideally be ISO-639 or BCP 47. If there is no code, the a temporary one is given (how?).
If full approval for the language is given, the pages will be transwiki'd into the new wiki. If not, the pages will either be deleted or kept to see if more improvements can be made (the langcom decides this?)
If the test is inactive for over a year, it will be deleted. The langcom can at any point decide that the test is no longer suitable and must be deleted.