Romanian ID Tag

[Robbob]

Hey All, this tag was dug up Kletskaya, Russia and has resided in my collection for a little while now, I finally dug it out and was hoping to get a little bit more information on it.
Not knowing to much about these types of tags I think I am right in saying that this soldier was recruited in 1942, his identification number was 3940 and his regiment was 5 AG? If anybody could give me any further information about this tag I would be very grateful!
Feel free to post any examples you might have!

[CTN]

I think AG means Artilerie Grea (Heavy Artillery). It could also mean Artilerie Gardă (Guard Artillery) or Artilerie Grănicerească (Frontier Guard Artillery) but I'm leaning towards the first option.

[Robbob]

Thanks for the extra info CTN. Much appreciated

[CTN]

MATR means matricol (registration) and CTG means contingent.