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Re: What is "f'(x)" as MathML?

From: Will Robertson <wspr81@gmail.com>
Date: Sat, 22 Jan 2011 19:50:02 +1030
Cc: David Carlisle <davidc@nag.co.uk>, "J.Fine" <j.fine@open.ac.uk>, Robert Miner <robertm@dessci.com>, Daniel Marquès Solé <dani@wiris.com>, "www-math@w3.org" <www-math@w3.org>
Message-Id: <2103338E-6C4A-4492-93D2-248E0A8811F3@gmail.com>
To: Frédéric WANG <fred.wang@free.fr>
On 22/01/2011, at 6:31 PM, Frédéric WANG wrote:

>> Indeed. In OpenType maths, (in any well behaved maths font) the prime symbol reverts to its non-subscripted form when the +ssty feature is enabled to indicate the symbols are for use in a subscript/superscript context. I don't know what the status is of browsers using OpenType font features, but following this practice would seem sensible to me.

> I'm interested in hearing more on that +ssty feature. A quick otfinfo on STIX, Asana and Cambria fonts shows that the first does not list that feature while the others do. How can we "enable" the feature and use it?

STIX does not have OpenType features yet but the XITS Math font does:
  <https://github.com/khaledhosny/xits-math>

Enabling a font feature requires that whatever program is using the font has some sort of understanding of OpenType; Microsoft Word, for example, has inbuilt support for the various maths layout features, as do XeTeX and LuaTeX. I have no idea if the types of programs used to render MathML (browsers and such) have this level of control over the fonts they are using; IMO they will have to in order to get sufficient quality in the long run.

Generally the "ssty" feature is equivalent to an "optical size" feature in which characters have some added weight/width to prevent them from losing too much colour when they're shrunk down to superscript size.

-- Will
Received on Saturday, 22 January 2011 09:20:41 GMT

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