# Design

The Sale Invoice Date Module introduces some new concepts and extends existing concepts.

## Invoice Term

The Invoice Term stores the method used to calculate the date of the invoice based on the moment the invoice is created.

See also

Invoice terms are created and managed from the main menu item:

> Sales ‣ Configuration ‣ Invoice Terms

## Sale

The Sale concept is extended to store the Invoice Term <model-sale.invoice.term> from the Party <party:model-party.party> or the Configuration <sale:model-sale.configuration>.

See also

The Sale <sale:model-sale.sale> concept is introduced by the Sale Module.