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

Re: rendering entities

From: <juanrgonzaleza@canonicalscience.com>
Date: Mon, 24 Apr 2006 04:38:51 -0700 (PDT)
Message-ID: <3118.217.124.69.210.1145878731.squirrel@webmail.canonicalscience.com>
To: <www-math@w3.org>

A couple of citations to MathML 2.0 specification

<blockquote>

3.1.1 What Presentation Elements Represent

Presentation elements correspond to the "constructors"
of traditional mathematical notation - that is, to the basic
kinds of symbols and expression-building structures out of which any
particular piece of traditional mathematical notation is built.
Because of the importance of traditional visual notation, the
descriptions of the notational constructs the elements represent are
usually given here in visual terms.  However, the elements are
medium-independent in the sense that they have been designed to
contain enough information for good spoken renderings as well.  Some
attributes of these elements may make sense only for visual media, but
most attributes can be treated in an analogous way in audio as well
(for example, by a correspondence between time duration and horizontal
extent).

[...]

Certain MathML characters are used
to name operators or identifiers that in traditional notation render the
same as other symbols, such as &DifferentialD;, &ExponentialE;, or
&ImaginaryI;, or
operators that usually render invisibly, such as &InvisibleTimes;,
&ApplyFunction;, or
&InvisibleComma;.  These are distinct notational
symbols or objects, as evidenced by their distinct spoken renderings and in
some cases by their effects on linebreaking and spacing in visual
rendering, and as such should be represented by the appropriate specific
entity references.

</blockquote>


<blockquote>

6.3.1 Special Constants

 To begin we list separately a few of the special characters which
MathML has introduced.  These now have
Unicode values.  Rather like the non-marking characters above, they
provide very useful
capabilities in the context of machinable mathematics.

[...]

Entity name    	 Unicode   Description

[...]

&DifferentialD;	 02146	   d for use in differentials, e.g. within integrals

[...]

</blockquote>

<blockquote>

The reasons for using specific mo elements for invisible operators include:

* such operators should often have specific effects on visual rendering
(particularly spacing and linebreaking rules) that are not the same as
either the lack of any operator, or spacing represented by mspace or mtext
elements;

* these operators should often have specific audio renderings different
than that of the lack of any operator;

* automatic semantic interpretation of MathML presentation elements is
made easier by the explicit specification of such operators.

[...]

3.2.5.6 Names for other special operators

MathML also includes &DifferentialD; for use in an mo element representing
the differential operator symbol usually denoted by "d".  The reasons for
explicitly using this special entity are similar to those for using the
special entities for invisible operators described in the preceding
section.

</blockquote>

In my opinion to use <mo>d</mo> instead of the entity because last is not
rendering adequately sound "a bit" tricky and I would discourage that
usage.

I believe one would be consistent with w3c emphasis of last decade on
eliminate tricky visual rendering -e.g. in XHTML-.

But more interesting still ;-) is next fragment I also obtained from the
MathML 2.0 specification and that has been unnoticed here apparently.


<blockquote>

2.3.3 Mixed Markup Examples

[...]

<mrow>
<semantics>
  <mrow>
    <msubsup>
      <mo>&int;</mo>
      <mn>1</mn>
      <mi>t</mi>
    </msubsup>
    <mfrac>
      <mrow>
        <mo>&dd;</mo>
        <mi>x</mi>
      </mrow>
      <mi>x</mi>
    </mfrac>
  </mrow>
  <annotation-xml encoding="MathML-Content">
    <apply>
      <int/>
      <bvar><ci>x</ci></bvar>
      <lowlimit><cn>1</cn></lowlimit>
      <uplimit><ci>t</ci></uplimit>
      <apply>
        <divide/>
        <cn>1</cn>
        <ci>x</ci>
      </apply>
    </apply>
  </annotation-xml>
</semantics>
</mrow>

[...]

In this example, we use the semantics element to provide a MathML content
expression to serve as a "semantic annotation" for a presentation
expression. In the display markup, we have used the
Msubsup element to attach a subscript and a superscript to an expression,
in this case the integral sign. We also used entities &int; and &dd; to
specify the integral and differential symbols.

</blockquote>



Juan R.

Center for CANONICAL |SCIENCE)
Received on Monday, 24 April 2006 11:39:00 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Saturday, 20 February 2010 06:12:58 GMT