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request for comments HTML WG comments to MathML WG

From: Shelley Powers <shelley.just@gmail.com>
Date: Wed, 4 Nov 2009 19:34:48 -0600
Message-ID: <643cc0270911041734h8c1ab5fh59435770b27edb14@mail.gmail.com>
To: HTMLWG WG <public-html@w3.org>
Following are the comments to the MathML WG in response to the group's
request for comments for MathML 3.0. Due to time constraints and size
of the MathML standard, the comments focus on those areas of change
from MathML 2.0 to MathML 3.0 [1]. As such, others are encouraged to
add to the comments in this email.

If you have any comments to add, or corrections, or recommendations,
please respond to this email and I'll make a second draft
incorporating comments before sending to the MathML Working group.

In addition, if you're familiar with directionality could you review
the new change to MathML for directionality [2]? It's not a subject I
or Joe are familiar with, but want to make sure there's nothing in the
section that could cause problems with MathML embedded in HTML5.

There are a lot of major changes with MathML 3.0, including removing
the entities to a separate document, and including the removal of the
DOM to a separate document.  Note, though, that the group only
references previous XHTML and HTML specifications, not HTML5. All of
the comments I've made are in relation to HTML5, and most are
reflecting MathML in HTML, not XHTML. Not sure what to do in this
regard.

Comments:

Comment one:

The attribute href has been added for use with several MathML
elements, rather than using xlink:href, from MathML 2.0[3]. However,
the document states that because of compound document requirements,
xlink:href can still be used. This could cause confusion when viewing
the documentation for  MathML as foreign object in HTML5. In the HTML5
specification, if the href attribute is associated with the XLink
namespace, it must be given as xlink:href in the document.

The MathML href attribute is now, by default, associated with the
MathML namespace. But this isn't specifically stated in the document,
and someone reading both may become confused, and assume they have to
use xlink:href with MathML embedded in HTML5. The document may want to
demonstrate how href can be used with embedded MathML in the document
section detailing MathML embedded in HTML.

(HTML5 folks: verify please that xlink:href does not have to be used
with MathML 3.0 embedding in HTML5)

Comment two:

MathML entities have now been moved to a separate document. These
entities will not be available with MathML embedded in HTML, served as
either HTML or XHTML, because there is no doctype. A warning to this
effect, and to use the equivalent Unicode or numeric character
reference, would be a useful addition to the MathML in HTML section.

Comment three:

The specification includes a section discussing MathML and HTML[4].
However, the section only references MathML in XHTML. With HTML5,
MathML can be used in HTML, and there are additional constraints on
using MathML in HTML, including the fact that the outer math element
is specified without a prefix (such as m:math, as shown in the
example), though the use of a namespace and prefix can work with
XHTML.

There are other constraints associated with MathML in HTML, as noted
in other comments. Could this one section be split in two, with one
section detailing MathML in XHTML, and one in HTML?

In particular, HTML allows unquoted attributes, and elements without
closing tags. These looser specifications also apply to foreign
objects such as SVG and MathML (though user agents are encouraged to
provide an export facility providing properly formatted XML). However,
people can paste properly formatted XML into HTML, and it will be
supported.

Pasting MathML into HTML does lead to another issue: the use of
namespaced attributes. Namespaced attributes can be included in
MathML, but are silently ignored. Currently, the validator does
provide a warning for namespaced attributes in SVG or MathML when
embedded in HTML. The same applies to properly formatted XML entities
and attributes that are included within the MathML annotation-xml
element.

Again, the validator warnings might be surprising to folks who paste
properly formatted XML into HTML.

Lastly, just an FYI for this section: the closing math element tag
isn't mandatory with HTML; the appearance of any element in the HTML
namespace will trigger an end to the Math markup.

end comments

There is a bug on HTML5 and MathML, and which MathML document is
referenced in the HTML5 spec[4]. I don't think the MathML group will
be overrun by weird crazy people, but MathML in HTML is a different
beast than MathML in an XML document, such as XHTML. There could be
changes in MathML in future versions that could adversely impact on
MathML embedded in HTML, where it wouldn't be an issue with an
XML-based format such as XHTML.

Shelley Powers
Joe Williams

[1] http://www.w3.org/TR/2009/WD-MathML3-20090924/appendixf.html
[2] http://www.w3.org/TR/2009/WD-MathML3-20090924/chapter3.html#presm.bidi
[3] http://www.w3.org/TR/2009/WD-MathML3-20090924/chapter2.html#fund.globatt
[4] http://www.w3.org/TR/2009/WD-MathML3-20090924/chapter6.html#interf.html
[5] http://www.w3.org/Bugs/Public/show_bug.cgi?id=7848
Received on Thursday, 5 November 2009 01:35:22 UTC

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