=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991
Boston              960/171 RLR(1964) is 11.0m below BM7
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 17-Aug-2011
Using NOAA data the RLR diagram was re-drawn. Primary benchmark is now K 12 MASS G.S. 1936 14.292 6.858m above gauge datum. Previous benchmark BM 7 is no longer listed on the NOAA site.