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XHTML: The New HTML Steven Pemberton Chair, W3C HTML Working Group.

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Presentation on theme: "XHTML: The New HTML Steven Pemberton Chair, W3C HTML Working Group."— Presentation transcript:

1 XHTML: The New HTML Steven Pemberton Chair, W3C HTML Working Group

2 Documents zHTML was designed for just one sort of document (scientific reports), but is now being used for all sorts of different documents zYou could use SGML to define other sorts of document, but SGML is notoriously hard to fully implement

3 Enter XML zXML is a W3C effort to simplify SGML zIt is a meta-language, a subset of SGML zOne of the aims is to allow everyone to invent their own tags zDTD is optional: a DTD can be inferred from a document

4 Consequences zThe requirement of being able to infer a DTD from a document has an effect on the languages you can define: yClosing tags are now required........ yEmpty tags are marked specially (or etc)

5 Consequences 2 zCDATA sections must be marked as such:

6 Consequence of XML zAnyone can now design a (Web-delivered) language zCSS makes it viewable Steven Pemberton CWI Kruislaan 413 1098 SJ Amsterdam

7 So do we still need HTML? zXML is still a meta-language zThere is still a perceived need for a base- line mark-up zHTML has some useful semantics, both implied and explicit (search engines gladly use it, for instance)

8 HTML as XML application zClean up (get rid of historical flotsam) zModularise – split into separate parts yAllows other XML applications to use parts yAllows special purpose devices to use subset zAdd any required new functionality (forms)

9 Differences HTML:XHTML zBecause of the difference between SGML and XML, there are some necessary differences, for instance: yUse lower case: not yAttributes are always quoted: yAnchors use id attribute not name:

10 Example Virtual Library Moved to

11 Namespaces A Math Example The following is MathML markup: 3 x

12 Semantics Differences zPresentation  use CSS zLinks  use Xlink and Xpointer (use ID not NAME) zForms  use CSS? zImages etc.  use Xlink z(Natural) language of elements  use xml:lang attribute

13 Transition zXHTML 1.0 has been carefully designed to make use of ‘quirks’ in existing HTML browsers zUse of a small number of guidelines allows XHTML to be served to HTML browsers

14 Examples of Guidelines zUse space before / of empty elements: zUse name= and id= on : …

15 Conclusions zXML with related technologies gives you the freedom to define and deliver your own document types zHTML is still needed as a base-line markup zThe new HTML gives a transition path to the future

16 The State of Things zNew generation of XML+CSS browsers emerging zMany XML applications appearing zMajor companies planning XML as output (Adobe PDF, MS Office 2000) zNow: HTML4 as XML, Conversion software zThis year: Modules, Subsets, Extensions, Profiles, New Forms

17 To Find Out More zAll XHTML developments are made public at zMembers of W3C can also look at


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