This hour you will learn what a metalanguage is and the basic structure of an XML metalanguage file, including how to use XML to specify rules that data must follow. Finally, you'll see how to extract data from an XML file and display it in a Web page.
(No HTML tags covered in Hour 23.)
A First XML File(Figures 23.1 - 23.3)
Like HTML, an XML file is constructed with tags. But in XML, the tags describe the structure of a language for communicating formatted information.
Reading XML Data(Figure 23.4)
This HTML contains JavaScript to read the data from the firstxml.xml file above. (Note that since the JavaScript does all the work, the actual body of the HTML document is empty.)
"Unlike the predefined tag names in HTML, user-defined tag names in XML have no intrinsic meaning. XML is not used to describe how information is to be presented in a display. The XHTML rules mentioned throughout the first 22 hours also apply to XML files. While is certainly an indication of good sense to use XHTML, it is not necessary to use it to display an XML file."