Unicode support for Troff-specific symbols

[John Gardner]

In Unicode 13.0, a new block
<https://www.unicode.org/charts/PDF/Unicode-13.0/U130-1FB00.pdf> was added
to support graphical symbols used on legacy systems,[1] particularly those
represented by obscure character encodings (like ATASCII
<https://en.wikipedia.org/wiki/ATASCII>).[2]

I'm wondering if Troff's non-representable symbols (listed below) are
eligible additions for this block. I'm envisioning their admission to use
names like:

\[sqrtex] radical symbol extension[3]
\(ul      troff under rule
\(ru      troff baseline rule
\(bs      troff client logotype[4]

Giving these characters a canonical representation in Unicode won't benefit
documents typeset by older troff(1) implementations, but it would simplify
documentation of future Groff releases and smooth out wrinkles in text
copied from gropdf(1) output.

Does this seem realistic to anybody else? Or have I developed tunnel vision
from dwelling on this idea too much?

Regards,
— John


   1. https://www.unicode.org/L2/L2022/22016.htm#170-C15
   2. A supplementary block
   <https://www.unicode.org/charts/PDF/Unicode-16.0/U160-1CC00.pdf>
   featuring Pac-Man and Space Invaders graphics has also been approved for
   the upcoming Unicode 16.0 (published next month). I think one of these
   "legacy computing" blocks gets the point across, however.
   3. Complements ⎷ (U+23B7 <https://graphemica.com/%E2%8E%B7> radical
   symbol bottom).
   4. I'm aware that corporate logos can't be added to the UCD (no matter
   how well-established they appear to be
   <https://emojipedia.org/apple-logo>), due to the conflict-of-interest
   regarding trademarks and brand representation. Hence why a more
   "diplomatic" name is suggested here, which relegates the exact appearance
   of \(bs to a font-level concern.