In responding to a question about a MIDI standard for band organs,
someone said that the manufactures got together and established
standards for MIDI instruments.  That is only partially true.

The initial MIDI standards included only communications specifications.
It was several years before "General MIDI" standards assigning
instrument numbers [voices] was produced.  I know for sure because
I own several "first generation" MIDI devices built by Casio and
Roland which do not conform to the General MIDI standard.

Wallace Venable