Datum is defined as what?

• A. The level plane used by bench marks to determine elevation and from which measuring begins
• B. A standard map scale
• C. A type of legal description
• D. A method of surveying by triangulation

Answer: (A)

A reference surface for elevations. In surveying, elevations must be measured from a defined zero point, and the level plane established by benchmarks provides that zero and from which all vertical measurements begin. This is the vertical datum, anchoring height data to a common reference (often approximating sea level). The other options describe different concepts: a map scale relates map distance to real distance, a legal description defines property boundaries, and triangulation is a method for locating positions by angles.