BR-KSA-F-01
A date MUST be formatted YYYY-MM-DD, in accordance to the "Calendar date complete representation" as specified by ISO 8601:2004, format YYYY-MM-DD.
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.
cbc:IssueDate | cbc:DueDate | cac:Delivery/cbc:ActualDeliveryDate | cac:BillingReference/cac:InvoiceDocumentReference/cbc:IssueDate | cac:InvoiceLine/cac:DocumentReference/cbc:IssueDates | cbc:TaxPointDate
(string-length(.) = 10 and (string(.) castable as xs:date))
Checked with Saudi Arabia ZATCA Tax Invoice (UBL), Saudi Arabia ZATCA Simplified Tax Invoice (UBL)