I'm new to xkb layouts, so my question may sound silly, but I having troubles understanding shift levels at all. As I get from docs, control and alt is supported modifiers. But if I edit those two lines in colemak layout from examples:

"shiftlevels": [ "None", "Shift", "Alt" ],

...

    { "pos": "J", "letters": [ "n", "N", "Left" ] },

then pressing Alt+n will trigger nothing. Same as if I added Control or Win to shiftlevels instead of Alt. The only modifier that triggers action is AltGr. Is that supposed behavior? Looking at examples I do see everywhere combinations of either Shift or AltGr and no other modifiers listed in docs, is this intentional? Or its smth wrong with my config that I get no action?