It sure is a massive subject and only an in depth knowledge of the period can differentiate one badge from another. No such thing as a neatly titled insignia like the French then!
Thanks also for the link. Very interesting read. The AK book is on my list to get and grateful thanks to Tony (a very patient man) for pointing me in the right direction there.
Give me 10 years (at least) and I might be able to join in with you guys!!!!!!