XV-MY-19
The supplier's tourism tax registration number is a mandatory field: cac:PartyIdentification/cbc:ID with schemeID TTX, NA when not registered.
warning: reported, still valid
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.
Context
/*/cac:AccountingSupplierParty/cac:Party | /*/cac:AccountingCustomerParty/cac:Party
Test
not($supplier) or exists($ttx)
Checked with MyInvois e-Invoice