Special Edition Using XSLT

XPath Data Model

In any computer language for manipulating data, the language defines a particular philosophy for thinking about what the data is. XPath considers data to be the nodes that represent XML documents, plus strings, numbers, and Booleans. The nodes are there to represent the XML document that the XPath expression is examining. Numbers and Booleans were added to make it possible to write complex expressions, such as selecting the fifth <line> within an <address> or the element satisfying the criterion of having both an address element and a name attribute. Likewise, strings are there to allow manipulation and comparison of the content of elements and attributes.

The Seven Node Types

As mentioned in Chapter 2, when a document is parsed, ...