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World Wide Web Consortium (w3c): XHTML Modularization - http://www.w3.org/MarkUp/Guide/xhtml-m12n-tutorial/
7 sections: introduction; terminology; module construction; DTD construction; module examples; mark-up language examples; usage examples. |
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Onaicul: XHTML Design Guide - http://www.onaicul.com/xdg.html
5 parts: introduction (including an historical perspective on hypertext); modularity; document specs; code guidelines; design guidelines; appendices with resources. Each part contains subsections. |
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Web Developer's Virtual Library (WDVL): Introduction to XHTML - http://www.wdvl.com/Authoring/Languages/XML/XHTML/
5 parts: introduction; XML and XHTML; document type definitions; differences from HTML; and document structure. |
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XHTML Tutorial - http://www.w3schools.com/xhtml/
8 pages, including introduction, differences from HTML, syntax, DTD, examples, validation, and a quiz. Also, reference pages provide lists of tags and attributes. |
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XHTML Tips - http://www.xhtmltips.co.uk/
A collection of help, guidance and tips to assist with web authoring. |