Hi GFA,
CASA in Australia = Civil Aviation Safety Authority.....
Makes the 'rules and regulations'.....
See the following suggested links for what it might be that you are enquiring about.....
Civil Aviation Safety Authority - Forms
This is the link for CASA Forms.
Civil Aviation Safety Authority - Home
This is the link for their 'Home Page'.
I think that this email system of communication is preferable to the AFTN.
I do hope this may be of assistance to you.
Good Luck
