public Parser dataValue() {
        if (dataValueParser == null) {
           FutureParser future = scoped("dataValue");
           dataValueParser = future;
           future.setParser(
               sequence(
                   optional(
                       token("BY")
                   ),
                   token("VALUE"),
                   plus(
                       choice(
                           token("ANY"),
                           sequence(
                               dataName(),
                               optional(
                                   sequence(
                                       token("AS"),
                                       typeName(),
                                       optional(
                                           attributeClause()
                                       )
                                   )
                               )
                           ),
                           typedefName()
                       )
                   )
               )
           );
        }

        return dataValueParser;
    }