Pete ah yes I see how that fits in although I'm afraid I can't explain A.F.W.
A1 is obvious enough but it does have a specific meaning & it does show that format of categorising was still functional. This is all that I have for the "A" category:
Able to march, see to shoot, hear well and stand active service conditions.
Subcategories:
Al Fit for dispatching overseas, as regards physical and mental health, and training
A2 As Al, except for training
A3 Returned Expeditionary Force men, ready except for physical condition
A4 Men under 19 who would be Al or A2 when aged 19