# Boundary Layers

Use this guide to choose boundary layers, find their lookup identifiers, and interpret geometry, statistics, and missing results.

## Choose layers

Supply at least one layer using `layers`. For multiple layers, send one comma-separated value, such as `layers=localities,localGovernmentAreas`. Names are case-sensitive. Duplicate names are processed once. The order of returned features is not guaranteed to follow the request order.

| Request value | Data returned | Primary PID field for identifier lookup |
| --- | --- | --- |
| `localities` | Suburb and rural locality boundaries | `localityPid` |
| `localGovernmentAreas` | Council area boundaries | `lgaPid` |
| `electoralBoundariesState` | State and territory electoral boundaries | `stateElectoralPid` |
| `electoralBoundariesCommonwealth` | Commonwealth electoral divisions | `commElectoralPid` |
| `absBoundariesMeshBlock2011` | 2011 Mesh Blocks and associated ASGS codes | `mbPid` |
| `absBoundariesMeshBlock2016` | 2016 Mesh Blocks and associated ASGS codes | `mbPid` |
| `absBoundariesMeshBlock2021` | 2021 Mesh Blocks and associated ASGS codes | `mbPid` |
| `absBoundariesMeshBlock2026` | 2026 Mesh Blocks and associated ASGS codes | `mbPid` |
| `absBoundariesRemoteness2016` | 2016 Remoteness Areas | `remoteness2016Pid` |
| `absBoundariesRemoteness2021` | 2021 Remoteness Areas | `remoteness2021Pid` |
| `absBoundariesSeifa2021` | 2021 socio-economic indexes for an SA1 | `seifa2021Pid` |
| `absBoundariesSeifa2011` | 2011 socio-economic indexes for an SA1 | `seifa2011Pid` |
| `absBoundariesSeifa2016` | 2016 socio-economic indexes for an SA1 | `seifa2016Pid` |

Use the identifier returned by this API, including its casing. ASGS codes and polygon PIDs are distinct from the primary PID used by `findByIdentifier`.

## Understand the boundary types

### Government and electoral boundaries

- **Localities** combine state and territory suburb and rural locality boundaries into a national representation
- **Local Government Areas** represent council areas. ACT has no Local Government Area feature. A lookup reports `Layer 'localGovernmentAreas' not found.` in `messages`. See the [Parliamentary Education Office's explanation of government responsibilities](https://peo.gov.au/understand-our-parliament/how-parliament-works/three-levels-of-government/the-responsibilities-of-the-three-levels-of-government)
- **Electoral boundaries** represent Commonwealth and state or territory electorates. State electoral attributes include effective dates and status, which help distinguish boundary versions

### ABS boundaries and statistics

- **Mesh Blocks** are the smallest ASGS areas. They aggregate into larger areas for statistical comparison. Their response attributes also identify associated Statistical Areas and Greater Capital City Statistical Areas
- **Remoteness Areas** group areas by relative access to services. They are derived from the Accessibility/Remoteness Index of Australia (ARIA+) and ASGS SA1 boundaries. Choose the required reference year
- **SEIFA** summarises relative socio-economic advantage and disadvantage using four indexes. Choose 2011, 2016, or 2021. Each response relates to an SA1 for that census year. Not every SA1 has SEIFA information. A point lookup finds the associated SA1 through the Mesh Block for that year

The four SEIFA indexes are:

| Field prefix | Index |
| --- | --- |
| `irsad` | Index of Relative Socio-economic Advantage and Disadvantage |
| `irsd` | Index of Relative Socio-economic Disadvantage |
| `ier` | Index of Economic Resources |
| `ieo` | Index of Education and Occupation |

Use the API schema for the returned scores, ranks, deciles, and percentiles. These are index measures, not percentages or physical units. See [ABS geography](https://www.abs.gov.au/geography) for ASGS background and contact [geography@abs.gov.au](mailto:geography@abs.gov.au) for ABS geography enquiries. The API's documented request values determine what you can retrieve.

## Geometry and missing data

- Set `excludeGeometry=true` when you only need attributes
- Geometry is excluded by default
- Set `excludeGeometry=false` when you need boundary coordinates
- Excluded geometry remains an object with `coordinates: [null, null]`. This is a sentinel value, not a usable polygon
- SEIFA always returns this sentinel geometry because it is an attribute lookup
- `areaSqm`, where supplied, is the area in square metres. Population and dwelling fields are counts
- Optional attributes without values are omitted
- Missing layers produce messages alongside a `200` result. Other requested layers can still return features

## Uses and examples

Boundary data supports geographic reporting, policy analysis, emergency management, and service-area analysis. Browse [Geoscape case studies](https://geoscape.com.au/our-impact/) for examples of location data in use.

## Next steps

- [Make your first boundary lookup](/guides/admin-boundaries/quickstart)
- [Review response schemas](/reference/~schemas)