The S Dist. Structure has four levels of hierarchy in census years, comprising in ascending order: CDs-SLAs-SSDs-S Dists. In non-census years, with CDs undefined, it has only three levels of hierarchy (see ASGC Structural Chart, Chapter 1).
In this structure, CDs, SLAs and SSDs are confined to those which fall within S Dists. The spatial units relate to each other through aggregation or disaggregation. For example, CDs aggregate to SLAs while SLAs are disaggregates of SSDs. The spatial units within each level of the S Dist. Structure do not collectively cover the whole of Australia.
The current S Dist. Structure, down to SLA level, is shown in Chapter 15 - The Classification Structures.
Statistical District Structure
(showing three hierarchical levels: S Dist.-SSD-SLA)