Field help (UOM4) 

Code consisting in 3 alphanumeric characters controlled in the units table. According to fields present, this code can concern the minimum quantity, the maximum quantity and the class for assigning free item data. It determines the number of decimal digits.
This unit can only be entered when it is used in the gross price calculation, or as an application criterion of the price list in general:

When the product is part of the criteria, the code is initialized with its sales unit and can be modified.