Datum line or datum point

A datum point or datum line is a known point of reference on the basis of which further measurements can be made. The line can be based on the finished floor level, an existing building or a benchmark.

When based on a benchmark, a datum line refers to a position above sea level. Benchmarks form a network of reference points from which a datum can be adopted. These are utilized in the construction of new houses, roads or stone pillars. A datum point can also be used in modeling geometry, where it’s possible to add several points on a model.