In this hierarchical schema, landscape features are grouped into varying levels
of detail. In the Anderson nomenclature, each hierarchy step is called a level. For
example,
level II Anderson, unit 10, is urban land. This unit is broken down into
eight constituent parts: low‑, medium‑, and high‑density residential; commercial,
industrial, and institutional; extractive; and open urban land. The fact that these
classifications
remain constant over a wide variety of analyses strengthens their usefulness
in, for example, trend mapping over time (where the necessity of similar
methods of classification is a given).