* All data (1963-85) supplied to the PSMSL to NN, with the above corrections
assumed to have already been applied.  Data 1986 onwards supplied to TGZ.
RLR(2000) is defined to be 6.565m below TGBM  
For data 1963-85 add 7.0m to all values to refer to RLR(2000) 
For data 1986-  add 2.0m to all values to refer to RLR(2000)
