Cover Inventory

I have a small Postal History collection, 1000 - 1500 covers. Mostly the 1851-57 issues (50%), 1861-65, Air Post and others. They are in 15 covered albums. I want to be able to locate specific covers by issue, city/town postmark etc. In order to do this I need to identify the covers by an inventory number. I have seen various methods used by dealers and they have often written that number on the back of the cover. I don't care to do that so I will use an Avery sticker on the sleeves. My question is what is the numbering system used by dealers? Are they unique to the dealer, does it represent the amount paid, is it a true inventor number or just a code of some sort.

Art

Art,

I think it is a code unique to the dealer on most covers. The only covers I've seen using a (inventory) Catalog # is flight covers listed by Am. Airmail Soc.

Dealers use their own systems, though I expect that more recently they are using ones that work with whichever computer program they are using to manage their business. Very often they incorporate some kind of code that tells them how much they paid for it and how long they have had it in inventory so when buyers bargain for a better price the dealer will know how low they can go and still make a good profit, or if it has been sitting in their inventory forever they may decide to unload it at cost or even a slight loss if it is a real dog and they know they overpaid for it.