AREA: Australian Standard Geographical Classification (ASGC)
The Australian Standard Geographical Classification (ASGC) is used for the collection and dissemination of geographical statistics. It incorporates several hierarchies of geographic areas (also referred to as spatial units) and defines the individual structures and the area types of which each structure is composed. Each geographic area in the classification is identified by an unique numeric code
The spatial units of the ASGC are arranged in several hierarchies. They indicate, for example, that Census Collection Districts (CDs), the smallest spatial units and area building blocks in the ASGC, form the lowest or most detailed hierarchical level of the classification. CDs aggregate, without gaps or overlaps, to Statistical Local Areas (SLAs) which in turn, represent another hierarchical level and aggregate without gaps or overlaps to Statistical Subdivisions (SSDs) etc.
For further details see ASGC