Use of tag characters in a private encoding - is it valid please?

[Erik Carvalhal Miller]

Although the angle brackets have Unicode names containing the word
“mathematical” and reside in the Miscellaneous Mathematical Symbols-A
block, I was thinking of their linguistic use for denoting characters qua
characters.  The single missing‐glyph glyph you originally saw between them
was the fallback display I expected in accordance with the Standard.

Note that UTS #51 encourages any implementation that supports emoji tag
sequences but has difficulty with a particular sequence to fall back by
displaying the base emoji either followed by or overlaid by a
“missing‐emoji glyph”; since in this case itʼs not likely that the PUA
character would even be recognized as an emoji, the fallback you saw is the
best‐case scenario one can expect in the absence of a private‐use agreement.

On Saturday, April 27, 2024, William_J_G Overington via Unicode <
unicode at corp.unicode.org> wrote:

> In the Unicode mailing list archive and in the webmail that I use the
> display was of the mathematical brackets with one glyph that indicates a
> missing glyph between them.
>
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