A datum is a reference framework used to describe positions or elevations. Survey and mapping work must identify the relevant horizontal and vertical datums, since values from different systems may not align. Project requirements and authority standards determine which datum applies. Surveyors document transformations and assumptions when information is converted between references.
Why it matters for owners
Datum mismatches can cause coordination errors across plans, records, and field work. Specify the reference system in contracts and deliverables.
