public Parser dtLinePos() {
        if (dtLinePosParser == null) {
           FutureParser future = scoped("dtLinePos");
           dtLinePosParser = future;
           future.setParser(
               sequence(
                   token("LINE"),
                   optional(
                       token("NUMBER")
                   ),
                   optional(
                       token("IS")
                   ),
                   optional(
                       choice(
                           token("PLUS"),
                           token("+"),
                           token("-")
                       )
                   ),
                   choice(
                       identifier(),
                       literal()
                   )
               )
           );
        }

        return dtLinePosParser;
    }