BR-CO-20
If Invoice line period (BG-26) is used, the Invoice line period start date (BT-134) or the Invoice line period end date (BT-135) shall be filled, or both.
What the rule checks
As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.
cac:InvoiceLine/cac:InvoicePeriod | cac:CreditNoteLine/cac:InvoicePeriod
exists(cbc:StartDate) or exists(cbc:EndDate)
Checked with EN 16931 Invoice (UBL), EN 16931 Credit Note (UBL), Croatia eRačun Invoice (UBL), Croatia eRačun Credit Note (UBL)
//ram:SpecifiedLineTradeSettlement/ram:BillingSpecifiedPeriod
(ram:StartDateTime) or (ram:EndDateTime)
Checked with EN 16931 Invoice (CII)