In our business we started using SKUs (stock keeping units) very early on. Mostly for my benefit because the difference between "Games Workshop Plastic Dwarf Warriors on Sprue" and "Games Workshop Plastic Ork Warriors on Sprue" is too subtle to quickly compute. My only other excuse is that I love numbers. They are so clear, appealing and often well rounded ;-) 

Anyway I like SKUs because they make sorting, picking and controlling stock easier. I prefer M3922 to something like "Vincent Black Shadow Bike with Side Car 1988" or "Citadel F2 Lords of Battle Sigismund Braveheart & Moritorus 1986" anytime.

We decided on short SKUs with a defining letter (C for Chaos, M for Marines, O for Orc/Orks and so on) plus a three digit number. By now with a lot of ranges we're in the four digits. Who'd have thought six years ago that we could sell so many thousands of used Warhammer units?

The next useful aspect of SKUs is that they adapt to changing stock needs like new product lines and you can incorporate location markers, codes for packaging requirements etc.

What you should never do is re-use them. Not too much of a problem in our business where there is ever only one unit with this SKU but fatal when you sell new products. When "Widget Sprog" has the code 350659-1194 and "Widget Sprog Version 2" 350659-1294 errors are inevitable. Especially when "Gadget Bit" has code 350660-2748, so the defining part of the code is in the middle of the number.

In the end SKUs are all about getting the right item to the customer and keeping your stock accounted for.

Lele