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

From: Philippe Verdy (
Date: Fri Jan 12 2007 - 10:36:48 CST

From: "Jon Hanna" <>
> 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.

This is definitely not what the TR says, which is much more general. It does not discourage their use for mathematical purpose only...

Note that the context is important because the TR also speaks about documents that mix both normal text and mathematics/physics (and even in the case of scientific formulas, and LaTeX maths documents, there are occurences of plain-text *within* formulas (for example to express conditions like "x is a prime number", or when using descriptive variable names).

I am not contesting the fact that use of the superscript 2 character must bediscouraged infavor of markup applied on regular number 2 when the notation really represents an exponent, and similar uses in indices. It's just the way this is formulated which will give wrong advices to implementers and to users.

The truth is that superscript/subscript markup should be used when its semantic is clearly separable from the semantics of the normal text being subscripted/superscripted, who also keeps its own semantic. Regarding the case of superscript in Mannan, its anusvara-like semantic (postnasalisation of vowels) is not separable like this into a consonnant n, and its text boundaries are not changing the standard baseline of characters. This character is in fact not a superscript as suggested by its glyphic appearance, but a plain letter with a distinct semantic.

This archive was generated by hypermail 2.1.5 : Thu Jan 18 2007 - 15:55:40 CST