So, what does the Ray Mask utility actually do?

[RRIS]

I read that it's an experimental feature.. is that still the case in Keyshot 8?
I'm currently using it to boost reflections on a metallic paint. I'm not sure if that's how it's supposed to be used, but it works great.
But yeah, what is it actually supposed to be used for?

[DMerz III]

  Oh... +1 on this!

[Peticel]

Hi. I've been using it to remove white spots created by Area Light Diffuse ( uncheck Visible Reflect on Ray Mask but leave it checked on Area Light ), make double sided materials and control shadows. Very useful. Would love to have it documented as well. Still not sure about Visible Gi ( Global illumination I guess ) as it seems to have no effect on normal or light emitting materials. I did not have too much time to experiment with this though.