Registered/Non-Registered Parameter Number (RPN / NRPN)

Controller number 6 (Data Entry), in conjunction with Controller numbers 96 (Data Increment), 97 (Data Decrement), 98 (Registered Parameter Number LSB), 99 (Registered Parameter Number MSB), 100 (Non-Registered Parameter Number LSB), and 101 (Non-Registered Parameter Number MSB), extend the number of controllers available via MIDI. Parameter data is transferred by first selecting the parameter number to be edited using controllers 98 and 99 or 100 and 101, and then adjusting the data value for that parameter using controller number 6, 96, or 97.

RPN and NRPN are typically used to send parameter data to a synthesizer in order to edit sound patches or other data. Registered parameters are those which have been assigned some particular function by the MIDI Manufacturers Association (MMA) and the Japan MIDI Standards Committee (JMSC). For example, there are Registered Parameter numbers assigned to control pitch bend sensitivity and master tuning for a synthesizer. Non-Registered parameters have not been assigned specific functions, and may be used for different functions by different manufacturers. Here again, Roland and Yamaha, among others, have adopted their own practices to assure some standardization.