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Sunday, February 17, 2008

W3C Last Call Working Draft: CSS Namespaces Module

W3C announced the release of an updated, Last Call Working Draft for
the "CSS Namespaces Module" specification, updating the previous WD
published 2006-08-28. The previous draft was edited by Peter Linss and
Chris Lilley. The deadline for comments is 7-March-2008. This CSS
Namespaces Module defines syntax for using namespaces in CSS. It defines
the '@namespace' rule for declaring a default namespace and for binding
namespaces to namespace prefixes. It also defines a syntax for using
those prefixes to represent namespace-qualified names. It does not
define where such names are valid or what they mean: that depends on
their context and is defined by a host language, such as Selectors,
that references the syntax defined in the CSS Namespaces module. Note
that a CSS client that does not support this module will, if it properly
conforms to CSS's forward-compatible parsing rules, ignore all
'@namespace' rules, as well as all style rules that make use of namespace
qualified names. The syntax of delimiting namespace prefixes in CSS was
deliberately chosen so that these CSS clients would ignore the style
rules rather than possibly match them incorrectly. A document or
implementation cannot conform to CSS Namespaces alone, but can claim
conformance to CSS Namespaces if it satisfies the conformance requirements
in this specification when implementing CSS or another host language that
normatively references this specification. Conformance to CSS Namespaces
is defined for two classes: (1) style sheet: a CSS style sheet or a
complete unit of another host language that normatively references CSS
Namespaces; (2) interpreter: someone or something that interprets the
semantics of a style sheet, where CSS user agents fall under this
category. CSS is the Web's primary style sheet language for specifying
the rendering of text documents, in particular those expressed in HTML
and XML-based formats. It can also be used to specify portions of the
rendering of certain non-text formats, such as SMIL (multimedia) and SVG
(vector graphics). The model of text-flow and the set of properties of
CSS are also shared with XSL, W3C's style language for complex formatting
of XML-based document formats, though XSL is developed by a separate WG.
In addition to visual output (screen, print), CSS also contains styling
properties for speech output. The CSS WG develops and maintains the CSS
language and related technologies. CSS allows both authors and readers
to specify the display or other rendering of documents, such as those in
HTML or SVG. CSS has several levels, from simple (level 1) to complex
(level 3) and several 'profiles,' which describe how CSS applies on
different media (TV, handheld, etc.). Level 1 is a Recommendation, level
2 is in maintenance, level 3 is currently being developed. More Information

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