XSL summary
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* XSL(extensible stylesheet language) is to XML what CSS is to HTML.
* XSL is a language that can transform XML into XHTML, a language that can filter and 
  sort XML data, a language that can define parts of an XML document, a language that 
  can format XML data based on the data value, like displaying negative numbers in red, 
  and a language that can output XML data to different devices, like screen, paper or 
  voice. 
* XSL consists of:
      XSLT: XSL uses XSLT to transform an XML source tree into an XML result tree.
      XPath:
      XSL Formating Objests
* The root element that declares the document to be an XSL style sheet is 
      <xsl:stylesheet> or <xsl:transform> - they are completely synonymous.