Why is there a stock position on the sales invoice?

Why is there a stock position o

n the sales invoice?

Did you mean stock quantity level by “stock position”? Please explain what you mean exactly.

The Inventory Location field appears because you have chosen an Inventory Item in your Sales Invoice line and you have defined at least one Inventory Location in Settings

The program assumes that you are following inventory levels by location, so when you sell an inventory item you are expected to say from which inventory location it has been sold from