1. Unit 3 — Advanced Internet Technologies Lesson 10 — Introduction to XHTML

2. Advanced Internet Technologies 2 Objectives Create simple XHTML documents. Recognize common HTML tags that do not conform to XHTML syntax rules. Transition HTML tags and attributes to XHTML format. Convert HTML attributes that do not include values. Transition HTML frame sets to XHTML.

3. Advanced Internet Technologies 3 XHTML Basics XHTML stands for eXtensible HyperText Markup Language. XHTML is based on the syntax rules of XML.

4. Advanced Internet Technologies 4 Basic XHTML Document Rules Many HTML documents must be transitioned to XHTML format. HTML transitioning means locating and correcting all HTML tags and attributes that do not conform to XHTML syntax rules.

5. Advanced Internet Technologies 5 Basic XHTML Document Rules (cont.) All XHTML documents must include a document type tag ( ). The tag contains the URL of a Document Type Definition (DTD).

6. Advanced Internet Technologies 6 Basic XHTML Document Rules (cont.) All XHTML Web pages must include an xmlns attribute within the main tag. The xmlns attribute specifies the URL of an XML namespace. An XML namespace defines a finite set of XML tags and attributes that will be considered valid in the current document.

7. Advanced Internet Technologies 7 Basic XHTML Document Rules (cont.) The XML namespace defined by the W3C requires all XHTML tags to appear in lowercase letters. (XML is case sensitive.) The XML namespace for XHTML transitional documents requires the presence of and tag pairs.

8. Advanced Internet Technologies 8 XHTML Character Encoding Although not strictly required, the header section of your XHTML documents should contain a meta tag to specify the desired character set. <meta http-equiv=“Content-Type” content=“text/html;charset=utf-8”>

9. Advanced Internet Technologies 9 XHTML Tag Pairs and Shortcut Tags Like XML, XHTML requires every opening tag to have a matching closing tag. XHTML also supports XML-style shortcut tags, such as.

10. Advanced Internet Technologies 10 XHTML Tag Attributes Like XHTML tags, all tag attributes must appear in lowercase. Like XML, XHTML requires all tag attributes to include values enclosed in double quotes.

11. Advanced Internet Technologies 11 More Useful Tags—XHTML Style Some common HTML tags that often cause problems in XHTML documents are,, and tags. These can be converted to XHTML shortcut tags. Some HTML tag attributes that must be modified to work in XHTML are SELECTED, READONLY, and DISABLED. Add =“true” to transition them.

12. Advanced Internet Technologies 12 XHTML Frame Sets Like HTML, XHTML supports frames and frame sets. XHTML frame set documents require the presence of a different DTD. The XHTML frame set DTD requires the presence of the tag pair rather than the tag pair.

13. Advanced Internet Technologies 13 XHTML Frame Sets (cont.) XHTML frame set documents use the same XML namespace as XHTML Web page documents. HTML frame set documents must be transitioned to XHTML in the same manner as Web page documents.

14. Advanced Internet Technologies 14 Summary You created simple XHTML documents. You learned common HTML tags that do not conform to XHTML syntax rules and how to recognize them. You transitioned HTML tags and attributes to XHTML format.

15. Advanced Internet Technologies 15 Summary (cont.) You converted HTML attributes that do not include values. You transitioned HTML frame sets to XHTML.