V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

XSL
       eXtensible Stylesheet Language (XML, XSL)


The Free On-line Dictionary of Computing (30 December 2018):

Extensible Stylesheet Language
XSL

    (XSL) A standard developed by the World
   Wide Web Consortium defining a language for transforming and
   formatting XML (eXtensible Markup Language) documents.

   An XSL stylesheet is written in XML and consists of
   instructions for tree transformation and formatting.  The tree
   transformations describe how each XML tag relates to other
   data and the formatting instructions describe how to output
   the various types of data.

   (http://w3.org/Style/XSL/).

   See also Extensible Stylesheet Language Transformations.

   (2005-09-30)