Cigar bar with inventory.
<example>
We have 6 cigars in inventory.
Customer 1 comes in and opens a tab/pre-auth and gets 4 cigars and takes them to the lounge to smoke with his friends. Leaves pre-auth open.
Customer 2 comes in and wants 4 of the same cigar, Inventory still shows the original 6 but only 2 are on the shelf.
Pre-auth open tab does not remove the cigars that customer 1 ordered. These do not remove out of inventory until the sale closes.