You can toggle 3 Stage Invoicing by navigating to 'Administration' > 'Setup' > 'Companies' and open the desired Company.
Go to the 'Settings' tab and tick the 'Use 3-Stage Invoicing' check box to enable 3-Stage Invoicing functionality for this Company.
The 3 stages of 3-Stage Invoicing are Sales Order, Delivery Note and then the Invoice. This process creates 3 documents whereas 2-Stage invoicing is comprised of a Sales Order and then an Invoice that contains an Invoice Delivery Number.
After generating an Invoice from a Sales Order, you will see that the Invoice has an Invoice Delivery Number assigned to it.
Delivery Notes generated using 3-Stage Invoicing will have their own dedicated table in the database. To view Delivery Notes and/or Invoice Delivery Numbers. Navigate to them under 'Documents' > 'Processing' respectively.
