Just looked into some of these and thought about whether or not I should carry these at the shop. Then thought, no. Even though they are a part of history, they would surely offend a significant percentage of my customers. Same reason I carry no Nazi coins/memorabilia. Some history is to be remembered, yet not honored by collecting it.
With no knowledge of how they were actually used, I would assume the tags would be held: A) Held on a huge key ring, sort of like a bearer tag. B) Worn on a neck shackle. I'm not sure of which it would be, but both make sense. In the first instance, the number would correspond to a number tattooed onto an individual, similar to a prison number. In the second, it would be for returning lost property. I still think the first version makes more sense, since it would seem very simple to remove the tag in the second case, if you were a runaway.
I think history is fascinating, even the bad stuff. I still cannot put myself to dealing with the swastika though - it was adopted by and had it's meaning so altered by evil and perhaps because there are still people living that have suffered under that regime and I have known several, I just don't feel comfortable even owning Nazi era coins.
It is estimated that over $300 million worth of Nazi gold was looted by Switzerland. Where did it go??? I have read reports about metallurgical testing done on the Swiss 20 Franc coins after 1946... Found that at least some of the gold was dental.
The Swiss or other coins made from Nazi dental work is a legend only. Steel, mercury, and other metals in dental work are separated when the gold is melted. There is no way to tell the source of gold in gold coins. Nazi gold could be in US, British, or any other gold coins made after 1945. By the way, for a long time I refused to own any coins from Mongolia because they would not apologize for the war crimes committed by Ghengiz Khan.
Gold recovered from dental gold WILL have traces of mercury in it. But when you are testing a gold bar and find tiny traces of mercury, is that mercury from dental gold, or is it from gold ore processed using mercury. That is a very common method of extracting gold from ore. And even if some how you KNEW it was dental, dental gold have always been recycled by dentists, people who have had crowns fall off, bridgework repaired or replaced etc. All of that dental gold gets recycled and leaved traces of mercury behind.