Negative/Negation Sign

[Asmus Freytag]

On 10/29/2022 1:31 PM, Gabriel Tellez via Unicode wrote:
> Looks like the real answer (hopefully) would be if we could find out 
> what U+207B SUPERSCRIPT MINUS was originally added for.

These characters were in Unicode from very early on. Unlike some of the 
later additions there is no link to a particular citation "in the wild". 
Instead, the original repertoire collected a superset of then existing 
character sets in reasonably wide usage. If any of their members 
violated Unicode encoding principles, they were added as compatibility 
characters (to facilitate round trip), otherwise as ordinary characters.

However, the question implicitly supposes that symbols and punctuation 
are encoded by function. That is not generally correct. They are encoded 
based on distinct (contrasting) shape compared to other symbols (noting 
that for dashes and similar symbols, shape is not only defined by the 
"ink" but also where that "ink" is placed). If a symbol was reused for 
something else without a change in appearance, it would not therefore 
qualify for being re-encoded.

In this case, the appearance of SUPERSCRIPT MINUS in a modern math font 
shows a relative positioning to superscript digits, full sized digits 
and relative length to the standard minus sign that matches to the TI 
character for negation (within the constrained imposed by limited 
resolution raster images).

I can see no indication that the TI engineers had some other symbol in 
mind, that is had they had the choice of a Unicode-encoded outline font, 
they would have chosen something with an appearance very distinct from 
SUPERSCRIPT MINUS. Unless and until someone can come up with a very 
cogent argument that they were really trying to model something that is 
visually distinct from a superscript minus sign, there is no reason to 
reject that mapping.

However, as I pointed out in another message, we should reject a mapping 
to 203E even though some sources have it: the visuals simply do not match.
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