Extensible Stylesheet Language (XSL)

The extensible stylesheet language (XSL) is an XML-based technology for transforming XML documents from one form to another. It uses a declarative programming paradigm and a specific XML namespace that gives programmers full access to all XML components - elements, attributes, and text - and the ability to manipulate them in ways that go far beyond the capabilities of cascading style sheets. XSL can be used to control the rendition of XML data, selectively filter the data items selected for transformation, convert data from various incompatible forms into a single, standard form, or implement just about any other operation that one might want to perform on XML data without changing the original XML source. Various parts of XSL are now industry standards (known as “Recommendations” by the World Wide Web Consortium) and are therefore highly usable even in today's ever-changing Web environment. This chapter presents the basic concepts and techniques used in XSL. It provides a variety of examples of XSL transformations (XSLT), XPath expressions (the language used to refer to collections of XML nodes for processing by XSLT), and XSL formatting objects. Keywords: cascading style sheets (CSS); stylesheet; XML; XSL formatting objects (XSL-FO); XSL templates; XSL transformations (XSLT)