Muse Sounds documentation

[ariutti]

Hello everyone,
I'll get straight to the point: what are MuseScore's virtual instruments and how do they work?

What data do they receive when playing the score (probably MIDI but not only, as @Tantacrul points out in this on video).

As far as I can see they are a bit like the ".sfz" format (have extension .sts and .spx).

Do they use samples from other available free sample library (like VCSL, VSCO-2-CE or SSO or they use specially recorded sounds?

Is there, or will be available, any documentation on the format they use, or on the MuseSampler software component (which, I believe, is the sampler that can interpret them)?

I was blown away by the way they sound! Even if they still need some fine-tuning, they are something stunning.
I am super curious to know more about how they work and I was not able to find details inside the handbook.