Norwegian has two official language variants, Bokmål and Nynorsk. Those have main variants Riksmål and Høgnorsk. The former does not have a valid language code while the later has a language code nn-hognorsk. I belive the code for Høgnorsk should be added.
I just tried to add “bok” as a variant in Lexeme:L1078, but it failed. “Bok” in definite singular is “boka” in Nynorsk and “boki” in Høgnorsk.
The English article about Høgnorsk can be found at w:Høgnorsk.