Sorry for the long response. Information about SMDv3 was originally found in leaked CSGO sources:
https://github.com/perilouswithadollarsign/cstrike15_src/blob/master/utils/studiomdl/v1support.cpp#L222

Hi. I need multiples UVs in my models, Valve's wiki says "SMD version 3 supports up to 8 additional UV layers after additional links." Can I export scenes to SMD v3 with Blender Source Tools?