Remove C1 support?
I added C1 support in bug 730154, to address the request of one person.
Now I think it was a mistake.
xterm deliberately doesn't support it in UTF-8. Which, in turn, guarantees that hardly any app emits it.
C1 is not without problems:
Supporting it is more cumbersome than I had hoped for. See e.g. 05c680ac and 181752d2.
Its support encourages others to use it, resulting in problems like Alacritty 3105.
Filtering out potentially dangerous characters (before printing untrusted data) becomes more complex, and makes it necessary to go into the locale business. Let alone security starts relying on the locale being set correctly; if the locale is misconfigured then there's a chance that a "dangerous" character (starting an escape sequence) can make it through to the terminal from an untrusted source. See mpg123 267.
Shall we change our minds and remove C1 support?