Usually, [1] is displayed. However, if any settings that affects the Invoice Issuance are changed during the Invoice Period, this number gets incremented to indicate something was changed during this Invoice Period.
This is the [Template (Invoice)] specified for this customer, defined in the [Item name] and this template is used for issuing the Invoice for this customer. If the template is not specified in the Contact Master, the template sheet chosen at the Select Template dialog will be used.
This parameter is to be used for filtering clients in the Invoice Issuance (for Cut-Off Date Invoice) or in the Delivery Entry screen. Please note that the system does not issue Invoices automatically upon the date set by this setting. 31 indicates the end of month.