The Enter Inv/Direct Bills/Credits (IN41) program is primarily used to Invoice system generated Sales Orders once the Order has been delivered. The program is also used:

To Invoice Customers for goods shipped from a manually prepared Shipping Document or for goods Directly Shipped from the Supplier to the Customer or to Invoice for charges other than Product sales (e.g. Freight).
To enter Credit Notes.
To enter Prebill Invoices and automatically auto-print the Order.
To enter Credit Notes and/or Direct Bills from RMAs.
To enter manually issued Invoices without assigning a system generated Invoice number.
To enter Floor charges (Invoices for EFT sales at Retail stores).

The following folders are available in IN41:

General
Miscellaneous
Lines
Total

For more information on each of these folders, click on the links above.