sap中如何配置根据销售订单进行Invoice

1. Assign the billing document type to sales order(VOV8)
2.The item category should be relevant for order related billing. i. e. to assign B(VOV7)
3.Set the copy control to create the billing document with reference to the order.

I am just enlisting the couple of example given in std R/3 which you can use for your reference.

A) Cash Sale.(Please note that you can only do billing after you had done PGI)
B) Credit memo request to credit memo.