Re: Public Review Issue Unicode Technical Report #25, "Unicode Support for Mathematics"

From: Jon Hanna (
Date: Fri Jan 12 2007 - 04:08:25 CST

Philippe Verdy wrote:
> I'm quite surprized at the conclusions given here about
"'discouraging" the use of
> superscript and subscript characters, despite there are languages
into which they are
>letters distinct from their respective baseline character counterparts.

"Despite?" That seems a very good reason for discouraging use of
superscript characters for mathematical superscripts. If there were no
other uses except for mathematics we could easily and reliably map
between superscript from markup and superscript for those characters,
but since there are languages in which they are letters distinct from
their respective baseline character counterparts it makes sense to
distinguish between such letters and mathematical or other uses of

> On the opposite, this paragraph does not speak about U+00AA (feminine
ordinal mark)
> and U+00BA (masculine ordinal mark) despite their meaning is clearly
derived from
> reagular small letters a and o.

Their being derived from a and o is largely just an interesting
historical fact, rather than any indicator of what they are now. ª is
not a and º is not o. Similarly I and i are encoded separately from J
and j and U and u separate from V and v.

The only possible relevance is that someone could double-abuse ª by
first using it as being a superscript a with no other semantics, and
secondly by using that superscript inappropriately contrary to what is
already said on this. That people are already discouraged from the
second part of this double-abuse it seems that while mentioning ª and º
might give a bit of extra advice and information, it is already covered
in what is stated.

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