Hello,
Re the note mentioned in your sources on the AWM Operational Histories WW2 - Air Vol.3 Chapter 9 'Second Libyan Campaign'.
www.awm.gov.au/collection/records/awmohww2/air/vol3/awmohww2-air-vol3-ch9.pdf
See footnote (5) on p.195.
For the revised Air Support Control System (September, 1941), see:
Strike from the Sky:The History of Battlefield Air Attack 1911-1945.
Hallion,Richard P.
Washington:Smithsonian Institution Press,1988.
p.155 (see also pp.152-8).
Col.