And there's an Australian convention about numbering where the address is an apartment/flat/unit in a block with its own street number.

So if Mr and Mrs Smith lived in a block of flats at 29 Acacia Grove, in flat number 42, it would be written "42/29 Acacia Grove".

But I would myself have expected to see (and to write in) this format:-

Mr and Mrs Smith
42/29 Acacia Grove
Como
WA 8564
AUSTRALIA

But the Australian post office likes the four-digit postcode to be written in large type away from and to the right of the address, anyway, so it often ends up looking like:-

Mr and Mrs Smith
42/29 Acacia Grove
Como
WA
AUSTRALIA .................... 8564

(Without the dots, of course.)