Denmarks were originally shorter and came in a Randall stamped sheath without the DS. Later examples of the first blade length were stamped as you can see my Rex's knife (very nice example). I have an earlier one, which I will try and dig up after I get fully un-packed from "the move".
Later on Denmark settled on the blade we know today, i.e. 4 1/2" length. It was also used (after Denmark closed it's doors) as an RKS "Club" knife before it was added to Randall's "Non Catalog" line-up.
Best, Capt. Chris