Adding 69 (decimal, or 0x45 hexadecimal) gives the number of semitones above the C five octaves below middle C. Not only is 440 Hz the standard central pitch for MIDI, it is also widely used as the "concert A" standard pitch (A4 e.g. USA, UK), and since that is represented in MIDI signals by the integer 69 (nine semitones above middle C (C4, c′), which is 60 decimal or 0x3C hexadecimal), this gives a real number which expresses pitch in a manner consistent with MIDI and integer notation, known as the MIDI note number, NMIDI .
The next two bytes (14 bits) specify the fraction of 100 cents above the semitone at which the frequency lies.
The precision pitch values may be used in microtonal music, just intonation, meantone temperament, or other alternative tunings.
Software plugin instruments which support MTS include Native Instruments FM8, Synthogy Ivory, and Xen-Arts' various xenharmonic VSTi plugins, including the FMTS FM synthesizer, Ivor virtual analog synthesizer, and XenFont SoundFont sample player.
Hardware instruments in current production which support MTS include: Dave Smith Instruments (DSI) Rev-2, Prophet-12, Prophet-6, Oberheim OB-6, Moog Sub37, Minitaur, Novation Bass Station II, Peak, Sonoclast Plastic Pitch Plus, and the Waldorf Kyra.