I agree with Herman. I've never seen an official document where you can read something about the regulations to a DJ knife and have never seen a picture of a of a kid wearing one. I have a calendar for the German state officers from the year 1936. In this book you can read that the HJ and DJ had a same knives(Fahrtenmesser). And BDM has no knives. I have in my collection a very late HJ knife with a RZM label with an inscription "HJ.-DJ. Fahrtenmesser", which confirms that both organizations had a same knives. Only my humble opinion.
