Initial point

A U.S. Bureau of Land Management map showing all of the principal meridians and baselines in the U.S. Public Land Survey System

In surveying, an initial point is a datum (a specific point on the surface of the earth) that marks the beginning point for a cadastral survey. The initial point establishes a local geographic coordinate system for the surveys that refer to that point.

An initial point is defined by the intersection of a principal meridian and a base line.