The Australian domain name system has rules. The following  rules apply to .com.au domain names:
.com.au is 2LD and is designed  for commercial business use.
Please read the policy rules when wanting to register a .com.au domain name.
You should also read the allocation policy which can be found on this website.
A

1/ an Australian registered company.

2/ trading under a registered business name in any Australian State or Territory

3/ an Australian partnership or sole trader.

4/ a foreign company licensed to trade in Australia.

5/ an owner of an Australian Registered Trademark

6/ an applicant for an Australian Registered Trademark.

7/ an association incorporated in any Australian State or Territory

8/ an Australian commercial statutory body.

B
com.au domain names must be.

1/ an exact match, abbreviation or acronym of the registrant’s name or trademark

2/ Otherwise be a close and substantial connection of the proposed registrant.

Cheaper Domains Pty Ltd is an auDA accredited registrar in the .au name space.

Indexed by Google, Yahoo and Bing natural search. First published 23.12.2010 copyright. Cheaper Domains is part of The Total Internet Group.