Validating XSLT Stylesheets
Numerous XSLT code quality assurance checks are done during automatic validation to help you keep your stylesheets valid and well-formed. Oxygen XML Developer performs the validation of XSLT documents with the help of an XSLT processor that you can configure in the preferences pages according to the XSLT version.
For XSLT 1.0, the options are: Xalan (Deprecated), Saxon 6.5.5 and Saxon 12.3. For XSLT 2.0, the option is: Saxon 12.3. For XSLT 3.0, the option is Saxon 12.3.
To access the XSLT
preferences quickly, use the 
Validation options action from the menu.