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Rendering primes: <msup><mi>x</mi><mo>&#x2032;</mo></msup>

From: <Justus-bulk@Piater.name>
Date: Thu, 26 Jun 2008 19:11:35 +0200
To: dev-tech-mathml@lists.mozilla.org, www-math@w3.org
Message-ID: <x8t1w2kt92w.fsf@tool.montefiore.ulg.ac.be>

Hi -

I'm slightly confused about proper markup and rendering of primes.

The W3C appears to recommend that primes be marked up as superscripts,
as shown in the subject line. This gave the expected results in
Mozilla back when I still used the LaTeX XFT fonts. That's normal: The
glyph used for the prime, codepoint U+0030 in cmsy10.ttf, is an
oversized, vertically roughly centered slab that is scaled and shifted
into just the right position and size by virtue of the superscript.

However, Unicode fonts these days provide a glyph (at U+2032) that is
quite evidently designed to be used without superscripting; its
position and size correspond to apostrophes and quotation marks. Using
the above markup, it is thus rendered too small and too high above the
baseline. (To see what I mean, point your out-of-the-box,
STIXBeta-powered Firefox3 to
http://www.w3.org/Math/testsuite/mml2-testsuite/Topics/Primes/primes1.xml
and compare the first x-prime to its sample rendering.)

So there is, I think, a contradiction between the recommended MathML
markup and the reality of glyphs.

As far as solutions are concerned, I think that W. Hammond's
suggestion
(http://www.albany.edu/~hammond/gellmu/primeaccents2.xhtml#mi) has its
merits. But if we stand by the <msup/> convention, then MathML
renderers will have to treat superscripted primes differently than
other superscripted characters.

Justus
Received on Friday, 27 June 2008 13:36:18 GMT

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