Some customers utilize Non-standard items on Sales and Purchase Orders for certain products which do not need history tracking. These are entered as a Line Type of N on the order documents. This is different than Non-inventoried items (P Line Type) which are saved in the product database for historical purposes. You can read about the differences in the two types of items here.
When utilizing this line type, the Unit of Measure (U/M) the Product Default Stocking Unit is shown on the Sales or Purchase Order. Once added, the user can select any U/M related to the default with a Standard, Weight, Length, and Variable relationship.