BR-AA-07
In a Document level charge (BG-21) where the Document level charge VAT category code (BT-102) is "Lower rate" the Document level charge VAT rate (BT-103) shall be greater than zero.
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:AllowanceCharge[cbc:ChargeIndicator='true']/cac:TaxCategory[normalize-space(cbc:ID)='AA' or normalize-space(cbc:ID) = 'RED' or normalize-space(cbc:ID) = 'INT']
(cbc:Percent) > 0
Checked with Portugal CIUS-PT Invoice (UBL), Portugal CIUS-PT Credit Note (UBL)