W3C home > Mailing lists > Public > www-math@w3.org > April 2006

Re: mover vs latin chars with diacriticals

From: White Lynx <whitelynx@operamail.com>
Date: Sat, 29 Apr 2006 13:28:47 +0400
To: www-math@w3.org
Message-Id: <20060429092847.40B3C2435B@ws5-3.us4.outblaze.com>

> If the spec is currently silent on this (maybe I missed where it talked about it), 
> do people think that the spec should recommend one form over the other?  
> If so which form?  
> [In case it is not obvious, I think <mover> should be recommended in the spec]

For me it is far from being obvious. There is Unicode standard that defines combining diacritical marks some of which are by design intended for usage in mathematical formulae.
Using redundant ad hoc markup instead of more universal Unicode solution that can be used in any XML application and even plain Unicode text is not the best option IMHO.
Note also that current font formats provide mechanism (OpenType, Graphite) 
that lets font designers to specify exact position of combining diacritical mark with respect to base character (STIX and Gentium are examples of such fonts).
In MathML approach it is unclear how MathML processor should retreive font metrics that ensure accurate positioning of accents. In addition note that Unicode standard specifies normalization mechanism that establishes correspondence between composed/decomposed characters (it is needed for string comparison/search purposes).

> My reading of this is that if your dot means differentiation, you should
> use mover.  If x-dot is just some wierd atomic symbol chosen by an
> eccentric author you should use the unicode.

As Juan already wrote, there is combining diacritical mark specially reserved for time derivatives.

> > [http://www.geocities.com/chavchan/userjs/support.xml]
> > 
> >Support for ANSI/NISO/ISO-12083 Mathematics DTD
> >
> > "Overscripts should not be used to produce accents, Unicode based
> > solutions (either combining diacritical marks, or precomposed characters)
> >  are preferable in this case."

> This is one person's opinion, not what ISO-12083 says.  As far as I could see, 
> 12083 is silent on the matter.  While it is informative to get another opinion on this, 
> implying that this is what 12083 says is false (at least as far as I could see in 12083's 
> math section).

That page describes what is preferable in concrete implementation (UserJS processor for ISO-12083) it does not quote ISO 12083 (that was developed before Unicode standard).


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Received on Saturday, 29 April 2006 09:30:59 GMT

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