In computing, the term Extensible Stylesheet Language (XSL) is used to refer to a family of languages used to transform and render XML documents.
Historically, the XSL Working Group in W3C produced a draft specification under the name XSL, which eventually split into three parts:
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 develops 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
This article is concerned with the various usages of the term XSL: for details of the various languages embraced by the term, see the relevant article.
XSL began as an attempt to bring the functionality of DSSSL, particularly in the area of print and high-end typesetting, to XML.
In response to a submission from Arbortext, Inso, and Microsoft, a W3C working group on XSL started operating in December 1997, with Sharon Adler and Steve Zilles as co-chairs, with James Clark acting as editor (and unofficially as chief designer), and Chris Lilley as the W3C staff contact. The group released a first public Working Draft on 18 August 1998. XSLT and XPath became W3C Recommendations on 16 November 1999 and XSL-FO reached Recommendation status on 15 October 2001.
"XSL" in Microsoft products
Microsoft's MSXML, first released in March 1999, contained an incomplete implementation of the December 1998 transformation language published in the W3C XSL Working Draft. Microsoft documentation used the term "XSL" to refer to this language as implemented in MSXML, including MSXML-specific extensions and omissions. Subsequently, when MSXML was updated to support the final W3C XSLT 1.0 Recommendation, Microsoft documentation referred to the obsolete dialect as "XSL" and to the new language as "XSLT". Other commentators follow the lead of Michael Kay in referring to the older language as WD-xsl. Current versions of MSXML (as of 2009) continue to support the obsolete dialect, but no longer mention it in the documentation.
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