While adding items to purchase orders Acme looks for the purchasing UOM in the following order:

 

1.Vendor item purchasing UOM

2.If blank, then fall back to the item's purchasing UOM

3.If blank, then fall back to the item's stocking UOM

4.If blank, then fall back to the stocking UOM set up in Acme options

5.If blank, then fall back to EA.

 

In most cases, vendors sell an item using the same UOM - so it comes from the item record. However, it is possible that an individual vendor may sell using a different UOM; vendor maintenance becomes an override of the item's purchasing UOM for that vendor.