Add 6.240m to data values 1964-1965 to refer to RLR<br>Add 6.107m to data values 1966-1969 to refer to RLR<br>Add 6.240m to data values for 1970 to refer to RLR<br>Add 6.107m to data values 1971 onwards to refer to RLR<br>RLR is 11.500m below primary benchmark SH Prefectura