=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991 Providence 960/158 RLR(1974) is 9.8m below BM6 =========================== FOLLOWING PSMSL DOCUMENTATION ADDED 17-Aug-2011 Using NOAA data the RLR diagram has been re-drawn.Primary benchmark previously known as BM6 has now been given the official name NO 6 RESET 1930 - it is still the same benchmark 4.493m above gauge datum.