The geographical location is reported using a five digit numerical code to indicate the Statistical Local Area (SLA) within the reporting state or territory, as defined in the Australian Standard Geographical Classification (ASGC) (Australian Bureau of Statistics (ABS), catalogue number 1216.0). It is a composite of state/territory identifier and SLA (first digit = state/territory identifier, next four digits = SLA).

The Australian Standard Geographical Classification (ASGC) is updated by the ABS on an annual basis, with a date of effect of 1 July each year.

Up until 2007, the ABS's National Localities Index (NLI) (catalogue number 1252.0.55.001) was available as a coding tool designed to assist users assign the ASGC Main Structure codes to street address information. However, the NLI is no longer produced by the ABS. To replace the Localities file of the NLI, the ABS has created a Locality to SLA correspondence file for 2011. This file is available on request by contacting ABS Geography at [email protected].