Learning XML

4.2. An Overview of CSS

This section takes a quick look at the major CSS topics.

4.2.1. Declaring the Stylesheet

To associate a stylesheet with your document, you need to declare it at the beginning so that the XML processor knows which stylesheet to use and where it's located. This is usually done with a processing instruction whose syntax is shown in Figure 4.5. Like all processing instructions, it will be ignored by any XML processors that don't need or recognize stylesheets. In this section, we discuss the subset of processors that actually transform XML into another format using stylesheets, such as web browsers that can format XML into a nice-looking page.

Figure 4.5. Syntax for a stylesheet declaration

The declaration begins with the processing instruction delimiter and target <?xml-stylesheet (1). The PI includes two property assignments similar to attributes. The first property, type (2), is set to the MIME type (3) of the stylesheet (for CSS, this is text/css). The value of the other property, href (4), is the URL of the stylesheet (5), which can be on the same system or anywhere on the Internet. The declaration ends with the closing delimiter (6).

Here's how it is used in a document:

<?xml version="1.0"?>
<?xml-stylesheet type="text/css" href="bookStyle.css"?>
<book>
  <title>Tom Swift's Aerial Adventures</title>

  <chapter>
    <title>The Dirigible</title>
  ...

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