Oooo, a test; we went through this just the other day!

Generally speaking......

Lets see now; The +10 point is where clipping may begin.

"0" is kinda like where all goodness resides, except on THX where it actually means some kind of reference point.

Ok, ok, I've been outta school for a long, long time! Might want to try a forum search!(or wait for a more in-depth responce)

Some recievers, like my onkyo, give you a choice: 0-100 and the relative +/-db scale. That's kinda cool.