code: public org.w3c.dom.Node getStylesheetNode(ExpressionNode ex)
    {
    	
      ExpressionNode owner = getExpressionOwner(ex);
  
      if (null != owner && owner instanceof org.w3c.dom.Node)
      {
  		return ((org.w3c.dom.Node)owner);
      }
      return null;
  
    }
docs: Get the XSLT ElemVariable that this sub-expression references.  In order for
  this to work, the SourceLocator must be the owning ElemTemplateElement.
  @return The dereference to the ElemVariable, or null if not found.