Everything has start from somewhere. The datum level is the best place to start
Land-surface datum is a datum plane that is approximately at land surface at each well. If known, the elevation of the land-surface datum above sea level is given... Datum: any level surface, line, or point used as a reference in measuring elevations.
A level
any level surface from which vertical distances of the points above or below this surface are measured is known as datum
The chart datum is about 825 mm below the mean sea level. This is usually a showing of the average of the lowest tides.
Datum is an imaginary vertical plane from which all horizontal measurements are taken with the aircraft in a level flight attitude.
Sea level rises and falls, so a datum line was put by the British Ordnance Survey on a harbour wall at Newlyn, Cornwall. It is from this datum line that mean sea level is measured.
Two:Datum is the singular of data.The experiment failed to produce a single datum of evidence.
The datum supporting my argument comes from my experiment outlined in my report.
A reduced level is the vertical distance between a survey point and the adopted level datum
'The data of the event is to be announced, but the majority of datum has been finalized.'
difference between the high flood level and stream bed datum.