Each Major Class code is a number from 001 to 999 and if you don’t have too many you will quickly remember them all. Another way to help you remember them is to assign them a three letter mnemonic code. For example if you choose major class code 125 for Ladies Ruby Rings you could assign the mnemonic LRR (or, if you prefer, RLR for Rings, Ladies Ruby.)
When you enter new inventory and you have to type the major class code you can type either the official major class code number or the mnemonic. Mnemonics are optional; you can assign one to every major code, just some major codes, or none at all.