private void validateIdentifierAttribute(Element element, Attr attr, ISchemaAttribute attInfo) {
   int severity = CompilerFlags.getFlag(fProject, CompilerFlags.P_UNKNOWN_IDENTIFIER);
   if (severity != CompilerFlags.IGNORE) {
     String value = attr.getValue();
     String basedOn = attInfo.getBasedOn();
     // only validate if we have a valid value and basedOn value
     if (value != null && basedOn != null && value.length() > 0 && basedOn.length() > 0) {
       Map attributes = PDESchemaHelper.getValidAttributes(attInfo);
       if (!attributes.containsKey(value)) { // report error if we are missing something
         report(
             NLS.bind(
                 MDECoreMessages.ExtensionsErrorReporter_unknownIdentifier,
                 (new String[] {attr.getValue(), attr.getName()})),
             getLine(element, attr.getName()),
             severity,
             MDEMarkerFactory.CAT_OTHER);
       }
     }
   }
 }