It certainly supports sending answerback: http://invisible-island.net/xterm/manpage/xterm.html#VT100-Widget-Resources:answerbackString http://invisible-island.

It certainly supports sending answerback: http://invisible-island.net/xterm/manpage/xterm.html#VT100-Widget-Resources:answerbackString http://invisible-island.net/xterm/manpage/xterm.html#VT100-W.... But IIRC, we had some (non-DEC?) terminals that 'helpfully' allowed remote programming of the answerback as well. I recall there was also a race to find other ways to get terminals to reflect content (send line, forms etc.).