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[Bug 9964] Namespaces section should be more explicit + touch the extensibility problem

From: <bugzilla@jessica.w3.org>
Date: Sat, 04 Sep 2010 00:55:04 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1Orh28-00067o-Ge@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=9964





--- Comment #2 from Eliot Graff <eliotgra@microsoft.com>  2010-09-04 00:55:04 ---
Edited section 5 to the following. I think I incorporated all of the comments
here, except the proposed 5.4 below. There's always the understanding that
other exceptions may be added at a later time.

5. Namespaces

The following rules apply to namespaces used in polyglot markup.
5.1 Element-Level Namespaces

[HTML5] introduces undeclared (native) default namespaces for the root HTML
element <html>, the root SVG element <svg>, and the root MathML element <math>.
The following default namespaces must be declared in polyglot markup, to
maintain XML-compatibility [XML10]:

    * <html xmlns="http://www.w3.org/1999/xhtml">
    * <math xmlns=http://www.w3.org/1998/Math/MathML">
    * <svg xmlns="http://www.w3.org/2000/svg">

Polyglot markup must not declare any other default or prefixed element
namespace, because [HTML5] does not natively support the declaring of any other
default or prefixed element namespace.
5.2 Attribute-Level Namespaces

[HTML5] introduces undeclared (native) support for attributes in the XLink
namespace and with the prefix xlink:. Polyglot markup must declare the XLink
namespace on the HTML root element (<html>) or once on the foreign element
where is used (<svg> or <mathml>), to maintain XML-compatibility [XML10].

In polyglot markup, the xlink prefix uses the namespace declaration
xmlns:xlink="http://www.w3.org/1999/xlink" before using the xlink prefix for
the following elements:

    * xlink:actuate
    * xlink:arcrole
    * xlink:href
    * xlink:role
    * xlink:show
    * xlink:title
    * xlink:type

Furthermore, polyglot markup defines the xlink prefix only on foreign elements
(any SVG or MathML element) but not the root <html> element or any other HTML
element.

Note that there are other prefixed attributes that can be used beyond
xlink:href (such as xml:base). Polyglot markup does not declare these prefixes
via xmlns. The prefixes are implicitly declared in XML and are automatically
applied to the appropriate attributes in HTML.

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Received on Saturday, 4 September 2010 00:55:05 UTC

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