r_bmodelhighfrac, s_leafnum, s_polykeep and s_polysize, what do they do?

[|B.A.M|The Tank]

Hey,

I am going through the default config cvars and try to explain what every command does. I was able to find all except for these ones. Can anyone shed some light on this matter?

[livewired]

s_leafnum, s_polykeep and s_polysize

I`m sure the s_ = sound, so are they to do with checking sounds depending on the leaf they are in or number of bounces off walls?