W3C:

2008-05-01: The XML Processing Model Working Group has published a Working Draft of XProc_ An XML Pipeline Language. This specification describes the syntax and semantics of XProc_ An XML Pipeline Language, a language for describing operations to be performed on XML documents. Pipelines are made up of simple steps which perform atomic operations on XML documents and constructs similar to conditionals, iteration, and exception handlers, which control which steps are executed. The status section of the document lists the most important changes since the previous draft. Learn more about the Extensible Markup Language (XML) Activity. (Permalink)