This specification is designed for MIDI controllers that allow the performer to vary the pitch and timbre of individual notes while playing polyphonically.
In many of these controllers, pitch is expressed by lateral motion on a continuous playing surface, while individual timbre changes are expressed by varying pressure, or moving fingers towards and away from the player. The MPE specification defines a MMA/AMEI Recommended Practice for hardware and software manufacturers to communicate multidimensional control data between MIDI controller instruments, synthesizers, digital audio workstations, and other products, using MIDI 1.0 messages. The specification describes a recommended way of using individual MIDI Channels to achieve per-note control without requiring Mono Mode (which would restrict polyphony to a maximum of 16 notes). This enables richer communication between increasingly expressive MIDI hardware and software. M1-100-UM MIDI Polyphonic Expression is a version 1.1 update which replaces the previous rp53 version 1.0. Version 1.1 has significant editorial improvements for clarity but has no technical design changes.