// ogc:Filter
locator = "ogc:Filter";
Node ndFilter = (Node)xpath.evaluate(locator,ndConstraint,XPathConstants.NODE);
if (ndFilter != null) {
IFilterParser parser = factory.makeFilterParser(context,constraintVersion);
if (parser == null) {
String msg = "IProviderFactory.makeFilterParser: instantiation failed.";
throw new OwsException(OwsException.OWSCODE_NoApplicableCode,locator,msg);
} else {
parser.parseFilter(context,ndFilter,xpath);