On 2025-12-25 09:40, [email protected] via Unicode wrote:
In L2/98-354 (https://www.unicode.org/L2/L1998/98354.pdf), the
following characters were proposed for DEC Technical Character Set
compatibility:
* E0AE Right ceiling corner DEC Tech 03/05
* E0AF Right floor corner DEC Tech 03/06
However, in L2/00-159
(https://www.unicode.org/L2/L2000/00159-ucsterminal.txt) which was
incorporated into Unicode 3.2, those characters were withdrawn:
E0AE Right ceiling corner U+2309 (1)
E0AF Right floor corner U+230B (1)
(1) These characters were in Unicode all along, but the shape shown in the
Unicode book was different from the shape on the terminal. However,
this is not sufficient reason to have two versions of the same symbol.
However, in DEC Technical Character Set (vt100.net)
<https://urldefense.com/v3/__https://vt100.net/charsets/technical.html__;!!BDUfV1Et5lrpZQ!Sz6zze1z-M_LTSPW0rIIzWUQNelFKnVEyxjuZ9heR5jLaL5gUpYG6I0qDcmkLRMrcElIb4gqD0QQLkFGildA6qyV$> the
usage of those characters is explained as being parts of the summation
symbol, and the left side of those characters connect to U+2500.
As far as I know, the floor and ceiling symbols usually have similar
height to brackets (with the horizontal stroke being on bottom or top
of the bracket height), and are used in pairs of left and right
glyphs, which is completely different from the DEC Tech 03/05 and DEC
Tech 03/06 characters. Is there any typographical precedent of floor
and ceiling symbols being used with a centered horizontal stroke or
with a horizontal connection to other characters?
The idea of "typographical precedent of floor and ceiling symbols being
used with a centered horizontal stroke" seems to me a non-sequitur from
the content at DEC Technical Character Set (vt100.net)
<https://urldefense.com/v3/__https://vt100.net/charsets/technical.html__;!!BDUfV1Et5lrpZQ!Sz6zze1z-M_LTSPW0rIIzWUQNelFKnVEyxjuZ9heR5jLaL5gUpYG6I0qDcmkLRMrcElIb4gqD0QQLkFGildA6qyV$>.
The latter alludes to a 2-d layout system by which parts of a sigma sign
is assembled from eight graphical components to make a 2x3 or 3x5
composite graphic. The former talks about formatting of linear plain
text with general-purpose fonts.
I can see the benefit of providing a mapping between the code units in
the DEC TCS and Unicode. I don't think that implies that ordinary plain
text and text formatting mechanisms should be able to perform the 2-d
layout described by DEC TCS. If I were implementing DEC TCS in a modern
OS and app, I would either use graphics mechanism to draw the sigma, or
an app-specific font where the glyphs have the size and relationships
which the app requires.
Does this answer your question? Or, reject the premise helpfully? Best
regards,
—Jim DeLaHunt
