invoice w/r sales order F1
invoice w/r delivery    f2
proforma invoice w/r order f5
proforma invoice w/r delivery f8

1) Sale Invoice with respect to sales order
2) Supplementary Invoice for Basic Price, freight difference
3) Scrap Invoice for Scrap sales
4) Deemed Export invoice for sales effected to 100% EOU.
5) Depot Sales Invoice related to stock transfer
6) Export Invoice

Invoice F5
Proforma Invoice F8 ( either order related or delivery 
related)
Invoice list
Credit & debit memo
External transactions
cancellation invoice
intercompany billing
Cash sales

By Defination Invoice(FICO) is A message to the buyer of 
goods or services that contains, among other things,

INVOICE SD  - sales and distribution document used to 
charge a customer for deliveryof goods or services.

The First Answer is appropriate 
F1, F2, F5,F8

Others
Invoice list
Credit & debit memo
External transactions
cancellation invoice

these are the supporting documents for the appropriate 
processing of invoices for that reason they are regarded  
as Billing Documents