What does the term "datum" refer to in real estate?

In real estate, the term "datum" refers specifically to a point, line, or surface used as a reference for measuring elevations. It serves as a baseline from which vertical measurements are taken, particularly in surveying and mapping. For example, in construction or land development, a datum might be established to ensure that all elevations are consistent and accurate. This is crucial for determining the relative height of a property, which can affect drainage, construction, and compliance with building codes.

In contrast, the other options present different concepts within real estate that do not align with the definition of "datum." Property valuation methods relate to how properties are assessed for market value. Ownership lines pertain to legal boundaries of property but do not involve elevation measurements. Zoning ordinances are regulations governing land use but do not address measurements or elevations. Thus, understanding what datum signifies is essential for activities involving land surveyor practices and real estate development.