It requires that all GS-compatible equipment must meet a certain set of features and it documents interpretations of some MIDI commands and bytes sequences, thus defining instrument tones, controllers for sound effects, etc.
In addition to the Sound Canvas series, Roland also provided GS compatibility in its own professional lineup through the JV-30 keyboard and the VE-GS1 expansion board for other JV-series instruments.
In addition, GS compatibility is provided in the GM2 specification which Roland helped to create and actively supports.
There were 16 additional drum notes that span Drum Kits 1 to 49: Additional controller events included in SC-55 and SC-88 were: There were messages that allowed the user to turn the GS mode on/off, to set effects processor parameters, to change EG envelopes etc.
Beginning in 1991, Roland introduced GS support in the majority of its consumer MIDI products.