I came across this interesting entry on the AIF First World War service record of a man who later transferred from the Light Horse Regiment to the Australian Flying Corps:

Letters “AUS” to be prefixed to Reg. No. (Sts 67th Sqn. AFC.)

Initially attached from the AIF/Light Horse to the RFC for a couple of weeks in Sep 1917 - for service with 67 (Australian) Squadron, RFC, the Squadron being redesignated 1 Squadron, AFC on 6 Feb 18 - the above entry related to the recording of his actual transfer to the AFC as an Air Mechanic 2nd Class and Fitter & Turner on 28 Sep 17.

I have worked through a number of AFC service records relating to New Zealanders but this is the first occasion on which I have come across an 'AUS' reference.

Presumably the introduction (temporarily?) of this prefix was to avoid confusion between AFC and RFC personnel when serving with a unit containing members of both services?

We are of course familiar with the AUS prefix to official numbers in the RAAF of WWII.