XSLT and XPATH: A Guide to XML Transformations

Chapter 4. XPath Expressions

• Expressions

• Location Path

• Patterns

• Axes, node test, and predicate

• Position()

• Abbreviations

XPath enables you to access parts of an XML document instance using “family affair” navigation relationships like ancestor, descendant, parent, child, and sibling. It provides the processor-readable (and human-readable) syntax for doing this, in the form of expressions.

In Chapter 1, we identified the tree structure by which XML addresses nodes in a document. In this chapter, we will explain the use of expressions, in the form of patterns and location paths, as well as location steps within those paths. We begin with the basic concepts of XPath, the XPath syntax and concepts like document order, context, and proximity. Chapter 5 ...