The specification is designed to provide a minimum level of performance compatibility among MIDI instruments, and has helped pave the way for MIDI in the growing consumer and multimedia markets. A minimum of either 24 fully dynamically allocated voices are available simultaneously for both melodic and percussive sounds, or 16 dynamically allocated voices are available for melody plus 8 for percussion.
All voices respond to velocity.
All 16 MIDI Channels are supported. Key-based percussion is always on MIDI Channel 10. A minimum of 16 simultaneous and different timbres playing various instruments. Respond to the data entry controller and the RPNs for fine and course tuning and pitch bend range, as well as all General MIDI Level 1 System Messages. The MMA's GM Developer Guidelines document describes additional recommendations and further clarifications of the GM Specification, which will insure improved compatibility among GM products.