FX-SCH-A-000103
An Invoice that contains a Document level charge (BG-21) where the Document level charge VAT category code (BT-102) is "Export outside the EU" shall contain the Seller VAT Identifier (BT-31) or the Seller tax representative VAT identifier (BT-63).
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.
[BR-G-04] An Invoice that contains a Document level charge (BG-21) where the Document level charge VAT category code (BT-102) is "Export outside the EU" shall contain the Seller VAT Identifier (BT-31) or the Seller tax representative VAT identifier (BT-63).
//ram:SpecifiedTradeAllowanceCharge[ram:ChargeIndicator/udt:Indicator='true']/ram:CategoryTradeTax[ram:CategoryCode = 'G']
(//ram:SellerTradeParty/ram:SpecifiedTaxRegistration/ram:ID[@schemeID = 'VA'] or //ram:SellerTaxRepresentativeTradeParty/ram:SpecifiedTaxRegistration/ram:ID[@schemeID = 'VA'])
Checked with Factur-X / ZUGFeRD MINIMUM