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Re: [MathML3-last-call] mathvariant

From: Sam Dooley <sam@integretechpub.com>
Date: Tue, 13 Oct 2009 09:51:30 -0600
Message-Id: <200910131554.n9DFs6dQ005998@parzival.integretechpub.com>
To: www-math@w3.org
Partially resolved with improved wording for section 3.2.2.

new revision: 1.281; previous revision: 1.280

Section 7.5 still needs updating to track changes in section 3.2.2.


<p>The <att>mathvariant</att> attribute defines logical classes of token
elements.  Each class provides a collection of typographically-related
symbolic tokens.  Each token has a specific meaning within a given
mathematical expression, and, therefore, needs to be visually
distinguished and protected from inadvertent document-wide style
changes which might change its meaning.  Each token is identified
by the combination of the <att>mathvariant</att> attribute value
and the character data in the token element.</p>


<p>In principle, any <att>mathvariant</att> value may be used with any
character data to define a specific symbolic token.  In practice,
only certain combinations of character data and <att>mathvariant</att>
values will be visually distinguished by a given renderer.  For example,
there is no clear-cut rendering for a "fraktur alpha" or a "bold italic
Kanji" character, and the <att>mathvariant</att> values "initial",
"tailed", "looped", and "stretched" are appropriate only for Arabic

<p>Certain combinations of character data and <att>mathvariant</att>
values are equivalent to assigned Unicode code points that encode
mathematical alphanumeric symbols.  These Unicode code points are
the ones in the <loc href="http://www.unicode.org/charts/PDF/U1D400.pdf">SMP
Mathematical Alphanumeric Symbol</loc> range U+1D400 to U+1D7FF,
listed in the Unicode standard, and the ones in the
<loc href="http://www.unicode.org/charts/PDF/U2100.pdf">Letterlike
Symbols</loc> range U+2100 to U+214F that represent "holes" in the
alphabets in the SMP, listed in <specref ref="chars_BMP-SMP"/>.
These characters are described in detail in section 2.2 of
<loc href="http://www.unicode.org/reports/tr25/">UTR #25</loc>.
The description of each such character in the Unicode standard
provides an unstyled character to which it would be equivalent
except for a font change that corresponds to a <att>mathvariant</att>
value.  A token element that uses the unstyled character in combination
with the corresponding <att>mathvariant</att> value is equivalent to a
token element that uses the mathematical alphanumeric symbol character
without the <att>mathvariant</att> attribute.  Note that the appearance
of a mathematical alphanumeric symbol character should not be altered
by surrounding <att>mathvariant</att> or other style declarations.</p>

<p>Renderers should support those combinations of character data and
<att>mathvariant</att> values that correspond to Unicode characters,
and that they can visually distinguish using available font characters.
Renderers may ignore or support those combinations of character data
and <att>mathvariant</att> values that do not correspond to an assigned
Unicode code point, and authors should recognize that support for
mathematical symbols that do not correspond to assigned Unicode code
points may vary widely from one renderer to another.</p>
Received on Tuesday, 13 October 2009 15:54:36 GMT

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