>> A debit invoice is for reversing vendor invoices. For AP invoices the menu item you are looking for is "Vendor Invoice"
It almost goes without saying that a menu option and the corresponding screen should definitely be have the same name. For example, if the screen is called "sales invoice", the menu option should also be "sales invoice".
Do people think it would be less confusing to rename "Sales Invoice" to "AR Invoice" and "Vendor Invoice" to "AP Invoice?"