ALL DUTCH METRIC DATA ARE MEASURED TO NAP (NORMAAL AMSTERDAMSCH PEIL)
PRIOR TO 1936 VALUES BASED ON HIGH AND LOW WATERS OR ON 4 OR 8 READINGS/DAY
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 08-Feb-2011
After receiving levelling data for NAP up to 2005 and the value of NAP after re-levelling in 2005 the station was made RLR. RLR factor up to 2005 6.929m and for 2005 onwards 6.946m.
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 22-Jan-2016
The note above stating that periods of the data are MTL is misleading.  Sections of the original data were MTL.  However, Pub. Sci. 5 states “For these periods a shallow water correction has been added to the mean heights of high and low water in order to give a mean height of sea-level comparable with those otherwise calculated for other periods.”  Thus, a correction to MSL has already been applied.

