Is ReGIS support uncommon? I know the terminal I use on Linux (mlterm) does, as does plain ol' xterm of course. (As an aside, it's annoying how many terminals set TERM to `xterm-256color` without being xterm compatible.)
I’m not sure - not many terminals advertise it. And yes - terminals lying on TERM is extremely annoying. Pretty much everything that has ever existed has a terminfo entry.