KEYARRAY
KEYARRAY specifies a type used to define an array of keys.
Each element in the array corresponds to a key-based percussion patch with each
of the 16 bits representing one of the 16 MIDI channels. Bits are set for each
of the channels that use that particular patch. For example, if the percussion
patch for key number 60 is used by physical MIDI channels 9 and 15, element 60
of the array should be set to 0x8200.
typedef WORD KEYARRAY[MIDIPATCHSIZE];