Invoiced field in sales_order_details

I am working on an import script for sales orders and I have not found any reference to what the invoiced field in sales_orders_details is used for.  Does 0 mean that it hasn't been invoiced and 1 mean it has been invoiced?  It is type double so maybe it is the quantity invoiced, or the total amount invoiced?  I don't see any reference to this field in the 2.3.x data schema so is this field a recent addition to FA?  Any insight would be helpful!

Thanks in advance!