To use the syntax higlighting extension with DocBook-XSL 1.74.3+, you must: 1. Use a processor that works with the extension: Saxon 6 or Xalan-J. 2. Add the latest version of xslthl-2.X.X.jar to your classpath. 3. Set the highlight.source parameter to 1. 4. Import into your customization one of the following stylesheet module: * html/highlight.xsl * xhtml/highlight.xsl * xhtml-1_1/highlight.xsl * fo/highlight.xsl 5. Use that customiztion layer. Note: Saxon 8.5 or later is also supported, but since it is an XSLT 2.0 processor it is not guaranteed to work with DocBook-XSL in all circumstances.