The MIDI 1.0 specification was released in 1984 in an attempt to end the Babel of proprietary interfaces that dominated the early days of electronic synthesis. This product of the MIDI Manufacturers Association (MMA), a consortium of large and small manufacturers of electronic musical gear, has been the backbone of live music performance for over 2 decades now. This is a testament to it's foresight and a clear acknowledgement of the need that it filled. Initially it specified only the basic interconnection of gear and a simple data protocol. The application layers were left to the manufacturers to define. This still made interconnection of gear from multiple manufacturers a challenge and patch and controller assignments had to be re-learned with each new piece of gear that one added to a rig. Eventually, separate application layers were defined; General MIDI and GM2, MIDI Machine Control, Standard MIDI Files, and MIDI Show control allowed true integration of equipment from multiple manufacturers to automate studios and live performance. This did not prevent proprietary extensions such as Roland's GS and Yamaha's XG extended GM sets.