XPath

XPath is a funded by::W3C-specified expression language for addressing portions of an based on::XML document, or for computing values (strings, numbers, or boolean values) based on the content of an XML document.

Implementations

 * Mozilla/JavaScript: Introduction to using XPath in JavaScript (using DOM Level 3 XPath)
 * Java: The Java XPath API

Resources

 * Specifications:
 * XPath 1.0
 * XPath 2.0