Allow selling items with zero quantity

[jacq7007]

I have the follow questions:
1) How can I setup my POS to sell stock with ingredients, with "Allow selling items with zero....quantities" de-activate.
2) How do I use Inventory categories & Units
3) What is the difference between Item Categories & Inventory Categories?

Thanks in advance.

[mblanche07]

I think I have seen a SELL with ZERO quan... to check off....under Preferences and Inventory