|Chapter 15||Extensible Markup Language (XML)|
The Schema in Fig. 15.12 indicates that every book element must contain child ele-ment title. If this element is omitted, the document is well formed, but not valid. If we remove line 8 from Fig. 15.11, XSV displays the error message shown in Fig. 15.13.
15.7 XML Vocabularies
|XML allows document authors to create their own tags to describe data precisely. People|
|and organizations in various fields of study have created many different XML vocabularies|
|for structuring data. Some of these vocabularies are: MathML (Mathematical Markup Lan-|
|guage), Scalable Vector Graphics (SVG), Wireless Markup Language (WML), Extensible|
|Business Reporting Language (XBRL), Extensible User Interface Language (XUL) and|
|VoiceXML™. Two other examples of XML vocabularies are W3C XML Schema and the|
Extensible Stylesheet Language (XSL), which is introduced in Section 15.8. The following subsections describe MathML, Chemical Markup Language (CML) and other XML vocab-ularies.
MathML markup describes mathematical expressions for display. Figure 15.14 uses MathML to mark up a simple expression. [Note: In this section, we provide sample outputs that illustrate how a MathML-enabled application might render the markup.]
|Fig. 15.14 Expression marked up with MathML. (Part 1 of 2.)|