Custom Keys

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This page documents every custom keycode implemented in the firmware.

CAPS_MOD

Location: CapsLock key (BASE layer and all FN layers)

CAPS_MOD replaces the standard CapsLock key with a context-sensitive multi-function key. Its behaviour depends on which modifier (if any) is held when you press and release it.

Action	Output
Tap (no modifier)	`Escape`
Hold (no modifier, past tapping term)	`Left Ctrl` -- acts as a regular Ctrl while held
`Shift` + Tap	Toggle CapsLock
`Alt` + Tap	Toggle Caps Word
`GUI` + Tap	Toggle Autocorrect on/off

How "hold = Ctrl" works: If you press CAPS_MOD and hold it past the tapping term without releasing, it registers Left Ctrl. Any keys typed while it is held are Ctrl-modified normally. Releasing CAPS_MOD unregisters Ctrl.

Modifier detection: When you press CAPS_MOD with a modifier already held, a harmless dummy keystroke (F24) is sent first so the OS does not interpret the modifier release as a bare tap (which would, for example, open the Windows Start menu on a GUI press).

BSP_DEL

Location: Not currently assigned to any key by default -- available for mapping via VIA.

BSP_DEL is a dual-function Backspace/Delete key.

Action	Output
Tap	`Backspace`
`Shift` + Tap	`Delete` (Shift is temporarily removed so the OS sees a plain Delete)

Layer Lock Keys

These keys are found on the number row when FN1, FN2, FN3, or FN4 is active.

Key	Position	Action
`LCK_FN1`	`1` key (FN1/FN2/FN3)	Toggle-lock FN1
`LCK_FN2`	`2` key (FN1/FN2/FN3)	Toggle-lock FN2
`LCK_FN3`	`3` key (FN1/FN2/FN3)	Toggle-lock FN3
`LCK_FN4`	`4` key (FN1/FN2/FN3)	Toggle-lock FN4
`LCK_CTL`	`5` key (FN1/FN2/FN3)	Toggle-lock KEEB_CTL
`LCK_BASE`	`0` key (FN1/FN2/FN3)	Clear all locks, return to BASE

How locking works:

Press LCK_FN1 while FN1 is active > FN1 stays on even after you release the FN1 key.
Press LCK_FN1 again while FN1 is locked > unlocks FN1 and returns to BASE.
Only one layer can be locked at a time. Pressing a different LCK_* key unlocks the current one.
LCK_BASE clears all locks unconditionally.
The , + . + / combo also clears all locks and returns to BASE as an emergency fallback. See Features -- Combos.

TT() vs LCK: The FN1 and FN2 keys on the bottom row use QMK's TT() (tap-toggle). A single tap + hold activates momentarily; a double-tap locks the layer on. The LCK_* keys are an additional explicit locking mechanism that works from inside any layer.

ALT_TAB_FWD / ALT_TAB_BWD

Location: Encoder (rotate right/left) while on FN2 layer

These keys implement a smart Alt+Tab window switcher:

Key	Action
`ALT_TAB_FWD`	Press Alt+Tab (cycle forward through windows)
`ALT_TAB_BWD`	Press Alt+Shift+Tab (cycle backward)

Smart Alt-hold behaviour: The first rotation press registers and holds Left Alt. Each subsequent rotation tap sends another Tab (or Shift+Tab). Alt is automatically released 750 ms after the last rotation event, committing the window selection.

This means you can spin the encoder multiple notches to skip several windows, and the moment you stop turning for 3/4 of a second the switcher closes -- no need to press anything to confirm.

CHORD_KEY

Location: Left Alt key, FN1 layer only

Activates Chord Unicode mode. While FN1 is held, pressing Left Alt enters (or exits) the chord input subsystem. See the Chord Unicode page for full documentation.