Additional version of Nynorsk (nn)?

Well, nn is the ISO 639 code, and the code nn-hognorsk is built according to BCP 47 which is the current standard for language+script+orthography+dialect etc. coding. be-tarask is being used, like several others the like, because there are two orthographies for Belorussian as well. What's the problem with all these? We're talking about localization, not about creating another wiki!

Greetings.