Australian Electoral Commission "socio-demographic" classifications

The AEC gives each seat what they call a socio-demographic classification (though they're more like geographic ones). You'll find their relevant page here.

Here's a copy and paste of their explanation:

All divisions are classified as being in 1 of 4 socio-demographic categories:

Metropolitan (divisions located in capital cities)

Non - metropolitan (divisions located outside capital cities)

With only four, some arbitrariness is inevitable. The lines between inner and outer metro, and outer metro and rural or provincial, and provincial and rural can be in the eye of the beholder.

Nevertheless, they work well for indicative purposes.

On pendulums and in tables, seats are given an R (for rural), p (provincial) o (outer metro) or i (inner metropolitan)

There are also two pendulums, metropolitan  and non-metropolitan