How can I reliably detect BD+?

[Silasqwerty]

Hello! I was wondering if every single BD+ has a BDSVM folder, and if that folder will always contain .svm files? I only have one, but I'm curious if that's something that every BD+ has to have, or if that might change depending on the version. Also, is it public knowledge how MakeMKV finds the version number for AACS and BD+? I tried looking at the files myself, but I couldn't find anything that outright states a version, and I'd be interested to know if that's something I could figure out without using MakeMKV.