Mike H,
The STYLE SETTINGS are 48 locations in ROM (4 per ROM style group) having 10 Ketron Programmed voices in each group [pg 48 of SD1 Owner's manual].
You cannot edit the contents of the voices per group (you will have to use the 1-TOUCH feature for this), but you can associate any of the 48 groups (with their pre-programmed voices) to any style on the SD1 [pg 51 of SD1 Owner's manual].
The Quick Guide, Hints and Tips manual for the SD1 also goes into some more detail and examples of such.
Thanks,
AJ