We consider 12/8 styles to be a 4/4 style with a triplet feel, rather than a time signature on its own. I realize that this doesn't cover the notation, for which 12/8 is a legitimate time signature, it is just for the playing of the style.

For example, is Moonlight Sonata a 4/4, 12/8 or something else?
If you google Moonglight Sonata Sheet Music, you will see that the same piece is written as 4/4 or 6/8. IMO, it is in 4/4 with a triplet feel.

So the point is that 12/8 and 6/8 are 4/4 time signatures, that have notation of 12/8, but should be thought of as a 4/4 style.

I'm not expecting to change anyone's mind on this (I've posted this before <G>), but just wanted to point out my thinking on the subject.

btw, 9/8 is a variation of 3/4.

Have Fun!
Peter Gannon
PG Music Inc.