M-key

An M-key (or "Mode key") is used on music keyboards and synthesizers to switch between different sets of controls or functions. Essentially, it acts like a toggle button that, when pressed, changes how other buttons or sliders behave—similar to changing the mode or context. For example, pressing the M-key might switch the instrument from controlling volume to adjusting effects. This feature allows musicians and producers to access multiple sound settings or control parameters without needing separate devices, making the instrument more versatile and efficient in live or studio settings.