The central component of the wild land reserve program. Core areas are large, allow little or no human use, and are taken mostly from public lands.

The total plane area of the portion of a grille, face or register bounded by a line tangent to the outer opening through which air can pass. The core area is less than the register size. Example, a 14X8 register may have a core that is 1" less than the listed size, therefore, the core area is 13X7=91 sq. in.

Area of heaviest use, may center on a resource, i.e. nest, water source, food source

The portion of a country that contains its economic, political, intellectual, and cultural focus. It is often the center of creativity and change (see Hearth).

The centre or focus of a particular activity where the majority of work or business is carried out.

That part of a sewer network containing the critical sewers, and other sewers where hydraulic problems are severe and merit detailed investigation.