Terminology - mcaple/tmk_keyboard GitHub Wiki

When a key is undefined on a particular layer, the key definition on the previously stacked layer will be used. Eventually the key definition will be set to using the default layer. If the None keyword is used, then the fall-through will stop and no action will take place.

When referring to keyboards, a key function that is only enabled until the release of the next keypress.

When referring to keyboards, a key function that is enabled until that key is pressed again (e.g. Caps Lock).

N-Key Rollover is the capability to press N number of keys at the same time on a keyboard and have them all register on the OS simultaneously.

Row x Column code or native protocol code used by the keyboard.

When referring to keyboards, a key function that is enabled while that key is held.

Keyboard Press/Release codes as defined by the USB HID Spec.