Statistical local area
Statistical local areas (SLAs) are for the most part local government area (i.e. legal LGA) based. In special cases, where a legal LGA is much larger and more populous than the general run of legal LGAs (as is the City of Brisbane), or where there are no legal local government authorities (as in the Australian Capital Territory), the administrative areas have been subdivided to form areas roughly equivalent in extent and population. SLAs cover, in aggregate, the whole of Australia without gaps or overlaps. The 1981 Census equivalent was the Census LGA.
They are identified by unique four digit numeric codes within a State/ Territory which have the following features:
(a) within each State/ Territory SLA codes are in the range 0001-9990, excluding those ending with 99. Codes ending with 99 and those within the range 9991-9999 have been reserved for special purposes;
(b) the arrangement of SLA codes within each State/Territory is in ascending numerical order for alphabetically listed SLAs. Gaps have been provided between the codes to provide space for future expansion or change;
(c) the fourth, i.e. last, digit of the SLA code is used as an indicator for the following characteristics:
0 indicates that the SLA equates with a legal LGA;
1-8 indicates that the SLA is a part legal LGA and gives each part a number; and
9 indicates that the SLA represents either, an unincorporated area, an off-shore/ migratory category or an undefined category.
Since SLA codes are unique only within State or Territory, for unique Australia wide identification State/Territory code and SLA code are needed.