Airfield Codes?

Not sure yet if this is correct but I suspect that certain airfields and stores parks, HQs etc in France in January 1940 were given a code. I have no idea if these are French, they could be airfields in the UK for all I know. Also given the large range of numbers involved I suspect that they may well refer to UK airfields (although the listings mights refer to all airfields in France and not just the RAF ones). What made me think that they may be French a/fs is that the source is the RAF Depot ORB and at that time, Uxbridge was supplying airmen to the Advanced Air Striking Force and the codes finish in May 1940 when Uxbridge started receiving airmen back from the BEF. If anyone can help please do:

A801
A802
A804
A806
A841
A844
A900
A901
A910
A913
A919
A924
A938
A939
A953
A958
A963

I wonder if they are codes for locations, towns railway stations etc. It would make sense if used on written orders or documents so that if captured by the enemy it would not disclose the locations.

Not thought of that PNK anything is possible.