Stock Categories offers an alternative classification of Stock Items. Like stock Groups, classification is done based on similarity in behaviour. The advantage of Categorizing items is that you can classify the stock items (based on functionality) together – across different stock groups which enables you to obtain reports on alternatives or substitutes for a stock item. It is not Mandatory. For enabling Stock Category option in the Inventory Info menu, press F11 > Inventory Features > Set Yes for Maintain stock categories .