You're exactly right, in the case of Trans-Mississippi regiments especially. As an example, someone looking for information about the (official) 39th Arkansas Infantry, would find practically nothing. You'd have to look up Cocke's Regiment, Hawthorne's Regiment, Johnson's Regiment, Polk's Regiment, the 6th Trans-Mississippi Infantry, and the 6th Arkansas Infantry -- of which are one and the same regiment -- and try to avoid confusion with the "real" 6th Arkansas Infantry, the "other" Johnson's Regiment, etc. And then once you've got that straight, you have to figure out which of the Company A's, B's, etc., you're looking for -- this regiment reorganized more often that I change shirts, and trying to keep up with the company redesignations, consolidations, etc., is a real chore. I've spent a lot of time trying to tie in all the various regimental designations, and while it ain't been easy, it's been an interesting piece of detective work.