Tab key is both a control character moving the cursor to the next input and also an input representing the tab character as you see in a text editor.
Now that im thinking about it I’m convinced capslock would have been superior next field key and alt+capslock to be used for toggling capslock. But it’s not obvious to me capslock [e: must be] seen by the OS. It could be changed on the keyboards themselves.
It definitely is visible, OS login screens usually warn you if caps lock is on when typing password
Thanks for the correction. I understand it is seen but wonder if it was in keyboard only in the past.
I don't think that would work, as capslock should only affect the letter keys (not e.g. turn "1" into "!") and the keyboard doesn't know which those keys are, as it depends on the layout configured in the OS.
Also, some layouts use shift lock (so actually turning 1 into !) instead of caps lock