ctrl+shift+_ is not emmitted

[soumith]

the key sequence for undo in emacs is ctrl + shift + - (- becomes _ on shift)
this sequence is not sent to the terminal, i.e. nothing happens.

[sigmonsays]

+1
is there a definitive list of key sequences that are emitted?

I'm noticing that screen key presses do not emit either (control-shift-A or control-shift+"). It's unclear what the expectation is and if we should just be using a lower level library than what term.js aims to provide.