qmk_firmware/docs/quantum_keycodes.md

Quantum Keycodes

Quantum keycodes allow for easier customisation of your keymap than the basic ones provide, without having to define custom actions.

All keycodes within quantum are numbers between 0x0000 and 0xFFFF. Within your keymap.c it may look like you have functions and other special cases, but ultimately the C preprocessor will translate those into a single 4 byte integer. QMK has reserved 0x0000 through 0x00FF for standard keycodes. These are keycodes such as KC_A, KC_1, and KC_LCTL, which are basic keys defined in the USB HID specification.

On this page we have documented keycodes between 0x00FF and 0xFFFF which are used to implement advanced quantum features. If you define your own custom keycodes they will be put into this range as well.

QMK Keycodes

Key	Aliases	Description
RESET		Put the keyboard into DFU mode for flashing
DEBUG		Toggle debug mode
KC_GESC	GRAVE_ESC	Escape when tapped, ` when pressed with Shift or GUI
KC_LSPO		Left Shift when held, ( when tapped
KC_RSPC		Right Shift when held, ) when tapped
KC_LEAD		The Leader key
KC_LOCK		The Lock key
FUNC(n)	F(n)	Call fn_action(n) (deprecated)
M(n)		Call macro n
MACROTAP(n)		Macro-tap n idk FIXME