Cameras are numbered according to the area of ground photographed, e.g. in a fan of four cameras, the camera photographing the ground on the extreme left would be numbered F41. F. S Indicates a starboard-facing oblique camera. P Indicates a port-facing oblique camera. N Indicates a nose-mounted oblique camera. If there is more than one, they are numbered from port to starboard, e.g. N1, N2 etc.
T Indicates a tail-mounted oblique camera.
This appears in figures only, e.g. 52 means No. 52 Squadron. This serves to distinguish between squadrons of the same number but belonging to different Air Forces. 5 Sortie number Sortie numbering for a squadron starts at 1 and ends at 9,999, when it goes back to 1 again. 6 Date This is shown in the form of 28 SEP 91. The focal length is useful in establishing the scale of the photograph.