Don't know what those notations mean, but FWIW I remind you of the futility of ascribing NM status to a rifle because there are several serials close to it in SRS. There was no serial block allocation for NMs, they were picked at random. In the Type 1 era 1953-1957, they were selected from regular rifles that shot straight in testing... one accurate one could be selected from less accurate brothers on each side of it. In late T1 1958-1959 and the Type 2 era 1960-1963 new NMs were built on any receiver that met specs, including WWII rebuilds. So forget SRS for evidence of possible NM status unless the serial is specifically listed.