https://c.aparatorul.md/otjtz
Let me guess: historical termcap. (-:
Might be Joy+Horton #vi, but my first guess is #termcap.
The way that termcap, and even terminfo, handle switchable stuff like this is truly terrible, because it simply does not fit their model. They're poor on input sequences anyway.
#FreeBSD still uses termcap(5), pretty much the only operating system left that does, and its manual page discusses how one might want to be compatible with AT&T #Unix S5R2 in the future.






