- XSL Transformation (XSLT): an XML language for transforming XML documents
- XSL Formatting Objects (XSL-FO): an XML language for specifying the visual formatting of an XML document
- XML Path Language (XPath): a non-XML language used by XSLT, and also available for use in non-XSLT contexts, for addressing the parts of an XML document.
As a result, the term "XSL" is now used with a number of different meanings:
- Sometimes it refers to XSLT: this usage is best avoided. However, "xsl" is used both as the conventional namespace prefix for the XSLT namespace, and as the conventional filename suffix for files containing XSLT stylesheet modules
- Sometimes it refers to XSL-FO: this usage can be justified by the fact that the XSL-FO specification carries the title Extensible Stylesheet Language (XSL); however, the term XSL-FO is less likely to be misunderstood
- Sometimes it refers to both languages considered together, or to the working group that developed both languages
- Sometimes, especially in the Microsoft world, it refers to a now-obsolete variant of XSLT developed and shipped by Microsoft as part of MSXML before the W3C specification was finalized
In response to a submission from Arbortext, Inso, and Microsoft,
The XSL family
The original version of XSLT (1.0) was published in November 1999, and was widely implemented. Some of the early implementations have fallen into disuse, but notable implementations actively used in 2023 include those integrated into the mainstream
Subsequent versions of XSLT include XSLT 2.0 (January 2007) and XSLT 3.0 (June 2017); there is work in progress on a version 4.0. These versions have not been as widely implemented as 1.0: the main implementations in widespread use in 2023 are Saxon (available in various versions for different platforms, including web browsers), and Altova's RaptorXML.
XSL Formatting Objects
Support for XSL Formatting Objects is available in a number of products:
- the XEP package from RenderXhas near 100% support for XSL-FO 1.0
- XSLFormatter from Antenna House also has near 100% support for the XSL-FO 1.0 specification and has 100% support for all new features within the XSL-FO 1.1 specification
- XINC from Lunasil has a great amount of support for the XSL-FO 1.0 specification
- XML2PDF Formatting Engine Server from AltSoft has near 100% support for the XSL-FO 1.1
These products support output in a number of file formats, to varying degrees:
- "Microsoft, ArborText and Inso Submit XSL Proposal to W3C". Sep 11, 1997.
- "XML and Semantic Web W3C Standards Timeline" (PDF). 2012. Archived from the original (PDF) on 2012-03-12. Retrieved 2021-04-08.
- "XSL language definition".
- "Extensible Stylesheet Language".
- Holman, G. Ken (2002-03-20). "What is XSL-FO". XML.com. O'Reilly Media, Inc. Retrieved 2008-09-01.