"alex.loubyansky(a)jboss.com" wrote : Fast jaxb doesn't parse schema itself. It maybe the SAX parser behind the scene. But the same SAXParserFactory is used by XB. All the initialization is in the test. XB does enable validation and schema awareness. There must be something else. Yes this is what I was referring to. Making sure they have identical sax parsers and configuration. One issue I just noticed is that the generated parser does a if/else switch style tree with equalsIgnoreCase(). JBossXB uses maps internally, so this could be one area of difference. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4257939#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...