See [doc/keycode.txt](https://github.com/tmk/tmk_keyboard/blob/master/doc/keycode.txt).
Keycodes are actually defined in [common/keycode.h](https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/common/keycode.h).
See [doc/keycode.txt](https://github.com/tmk/tmk_core/blob/master/doc/keycode.txt).
Keycodes are actually defined in [common/keycode.h](https://github.com/tmk/tmk_core/blob/master/common/keycode.h).
## Sysrq key
Use keycode for Print Screen(`KC_PSCREEN` or `KC_PSCR`) instead of `KC_SYSREQ`. Key combination of 'Alt + Print Screen' is recognized as 'System request'.
Modifier keys or layers can be stuck unless layer switching is configured properly.
For Modifier keys and layer actions you have to place `KC_TRANS` on same position of destination layer to unregister the modifier key or return to previous layer on release event.