Geodesists and surveyors use datums to create starting or reference points for floodplain maps, property boundaries, construction surveys, levee design, or other work requiring accurate coordinates that are consistent with one another. There are two main datums in the United States.

Why do we use a datum?

A datum is a plane, a straight line, or a point that is used as a reference when processing a material or measuring the dimensions of a target.

What is the purpose of datum planes?

Datum planes are features used to provide references for other features, like sketching planes, dimensioning references, view references, assembly references, and so on. Datum planes are not physical parts of the model, but are used to aid in model creation.