=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991
Progreso            920/001 RLR(1964) is 13.8m below BM1
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 29-Jul-1993
Anomalously low value May 1959 - correct as received from authority.
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 12-Jan-2012
Regarding the comment above re. the data spike in May 1959. In the old system it was only possible to flag a whole year as suspect. This is not the case with the new database. As the rest of the data for 1959 looks correct the flags have been removed so May 1959 is the only month flagged.
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 24-Jun-2015
Levelling information has been received from UNAM. Primary benchmark remains BM 1. However the TGZ is now 12.301m below BM 1.

