xkb - Keymaps at `/usr/share/X11/kbd/symbols` 2 values vs 4 values being specified I was checking the keymap found at `/usr/share/x11/kbd/symbols` and in particular, I was browsing the `us` keymap and I didn't understand how this works: > key `<TLDE>` { [dead_grave, dead_tilde, grave, asciitilde ] }; I understood that: > key `<TLDE>` { [ grave, asciitilde ] }; meant that for regular keypress of ```, I would get `grave` on the screen and pressing `Shift`+``` would result in `asciitilde (~)`. So, how can 4 values be represented?

The other two values are for `ISO_Level3_Shift` and `ISO_Level3_Shift+Shift` (`ISO_Level3_Shift` generally corresponds to the AltGr key).