[BR-CO-19]-If Invoicing period (BG-14) is used, the Invoicing period start date (BT-73) or the Invoicing period end date (BT-74) shall be filled, or both.
Stored validation assertion
exists(cbc:StartDate) or exists(cbc:EndDate) or (exists(cbc:DescriptionCode) and not(exists(cbc:StartDate)) and not(exists(cbc:EndDate)))