MIDI Manufacturers Association
Since its introduction in 1983, all MIDI-related technology has been maintained by the MIDI Manufacturers Association (MMA).
All current and future MIDI standards are developed and officially published by the MMA in the US or the MIDI Committee of the Association of Musical Electronic Industry (AMEI) in Japan.
The official reference for MIDI is available from the MMA or AMEI and is entitled The Complete MIDI 1.0 Detailed Specification, document version 96.1.
The official MMA website is available at MIDI.org