tailieunhanh - XML Step by Step- P13

XML Step by Step- P13:Extensible Markup Language, or XML, is currently the most promising language for storing and exchanging information on the World Wide Web. Although Hypertext Markup Language (HTML) is presently the most common language used to create Web pages, HTML has a limited capacity for storing information. In contrast, because XML allows you to create your own elements, attributes, and document structure, you can use it to describe virtually any kind of information from a simple recipe to a complex database | Chapter 8 Displaying XML Documents Using Basic Cascading Style Sheets 211 note If the browser can t find the style sheet file specified in the xml-stylesheet processing instruction it will display the document text using its own property settings for example its current font and font-size settings . And as you learned in Chapter 2 if the XML document isn t linked to a style sheet that is the document doesn t contain an xml-stylesheet processing instruction Internet Explorer will display the XML source for the document rather than its content. You can include more than one style sheet in an XML document by inserting an xml-stylesheet processing instruction for each one as in this example of the beginning of an XML document xml version xml-stylesheet type text css href xml-stylesheet type text css href INVENTORY -- contents of document element. -- INVENTORY Basic Cascading Style Sheets 8 The option of linking several style sheets allows you to store groups of related rules in separate files and then combine them as needed for particular types of XML documents. When you link more than one style sheet Internet Explorer merges the rules from the different sheets. If separate style sheets contain conflicting rules the rules in a style sheet linked later in the document take precedence over those in a style sheet linked previously in the document. In the preceding example rules in would have priority over conflicting rules in . You ll learn more about precedence among conflicting rules in the next section. Cascading in Cascading Style Sheets The cascading in Cascading Style Sheets means that you can assign values to properties at several different levels just as a cascading stream spills through different levels . The following list describes the main levels at which you can assign a value to a property. The levels are listed in their order of precedence from highest to lowest. When the browser goes to display an element if a