Hi
Yamaha styles can hold different patterns for the chord types Kari listed in any combination. You have the 16 MIDI channels for this.
In Yamaha style channel 9 and 10 are for drum and percussion. The remaining 14 channels can be used for different patterns to the remaining style parts (bass, chord1, chord2, pad, phrase1 and phrase2).
Lets us say you want to have 4 different bass patterns you will now have 10 channels to the rest of the style parts.
In the CASM section the 4 source channels which holds the 4 bass patterns are redirected to output channel 11, which is the Yamaha specification for the bass channel.
You can read more about this at The Unofficial YAMAHA PSR Resource Site
at
http://home7.inet.tele.dk/js/musik/740pages/ Follow menu PSR Links -> Articles
Jørgen