Re: [NTG-context] mml

On Thu, 30 Mar 2006 23:02:10 +0200, Hans Hagen wrote:

nico wrote:

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On Thu, 30 Mar 2006 10:18:32 +0200, Taco Hoekwater wrote:

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Hi nico/Hans,

Hans Hagen wrote:

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<mo> ¯ </mo>

The MathML spec specifically suggests the use of ‾ instead of a literal accent character in situations like this.

The problem is that it is also specified to which unicode character is mapped the entity (http://www.w3.org/TR/MathML2/isodia.html). Actually ‾ is U00AF.

the messy part is that

- a macron has no stretch - an overbar has stretch

so, while there is a lot math stuf (now) in unicode, the macron is used for an overbar which is rather strange; do they also 'misuse' the underscore for underbar etc?

I guess that in MathML stretchiness is more systematic and should apply to most characters, provided that they can stretch (http://www.w3.org/TR/REC-MathML/chap3_2.html). In this doc it is said: "By default, most horizontal arrows and some accents stretch horizontally."

now an implementation needs to adapt to math or text (or just gamble since it may be that i want a non stretchable macron over x+y+z); my guess is that as a result, many implementations are more complex than needed

From my little window (since I don't know how it works internally) I would say that in mathml stretchiness is required in things like <mover> or <munder>, if the character allows it, and depending on stretch attribute. But it's sure that it does not make things easier.

(btw, in pure text, it's still not clear if the macro glyph sould be chosen or a stretchable hrule)

What is not clear to me is if unicode explicitely allows a combination of a non spacing mark (accent) and a *group* of characters. In the specification I've only seen that it can apply to a base character. If it can apply only to one character, a glyph seems enough.

(i think that one problem of unicode/xml/mathml is that it is used in typesetting systems but not in all aspects is designed (or used) to facilitate high end results; therefore a 24/32 bit tex still needs to provide much detailed control)

Yep! Regards, BG