XSLT and XPATH: A Guide to XML Transformations

5.1. XPath Function Library

The function library for XPath includes 27 functions, called Core Functions, which are divided into four subcategories: node-set, Boolean, string, and number. The four kinds of functions within the function library are categorized not necessarily by the object they yield, but also by the object on which they act. The object on which they act is called an argument.

In the following section, each function will be discussed individually within the core function group subcategory—based upon either the kind of object yielded or the kind received (i.e., “acted upon”) as an argument—for that function.

Functions sometimes will yield different kinds of objects than the core function type to which they belong. It is important ...