Message

An invoice period end date MUST be later or equal to an invoice period start date

Context
//cac:InvoicePeriod
Test
(cbc:StartDate and cbc:EndDate) and (number(translate(cbc:StartDate,'-','')) <= number(translate(cbc:EndDate,'-','')))
Usage
/ ubl:Invoice / cac:InvoicePeriod / cbc:EndDate