Been a few years since it was my trade, but
The RAAF use a SQN or Unit based call sign allocation.
For example,
2FTS Unit Callsign is VIPER, this can be used as an indvidual aircraft callsign with the personal (number) identifier ie VIPER 262.
Or as a formation/multi aircraft sortie with an unit allocated formation calsign
ie VIPER VAMPIRE
The unit or SQN may also have unique or specialist calsigns such as TANGO for I believe solo students.
International flights all use the AUSSIE (xxxxxxxxx) calsign.
Unit/SQN calsigns are usualy have a historical significance to that unit or SQN. Once you get a handle on the calsigns you can quickly determine type and sometimes number of aircraft with just one listen, good for Situational Awarness and sometimes just plain usless info.
I could not get into the website mentioned earlier, and I would be here all night listing the SQN/Unit C/S and Formation C/S. but hera a few of the faves.
Classic (75SQN F18/Mirage IIIO) Condor, or as they were better known, Plastic cardoor.
Pan Pan Panthers, (2OCU M32)
Ramrod, can't remember who had that one F111 I think, but COOL anyhow.
Goodnight Duckhole
richo