Point of Sale : How to update stocks in Zoho Inventory through API

Point of Sale : How to update stocks in Zoho Inventory through API

Hi,

We have a retail shop with an external POS system. I would like to update the product stocks every time a product is sold in the shop. How should I do that.
I was thinking of using Item Adjustment but the description does not really fit that need : " Item Adjustments are used to synchronize the inventory/stock to account for things that occur outside the normal business like theft, damaged goods, data entry error etc."

Should I create a sale order instead ? I won't always have a customerId to attach to the order so it looks a little over-engineered, no ?
Is there a tutorial that explain best practices on how to integrate external sales platform with Zoho Inventory ?

Nicolas