FX-SCH-A-000100
In a Document level charge (BG-21) where the Document level charge VAT category code (BT-102) is "Reverse charge" the Document level charge VAT rate (BT-103) shall be 0 (zero).
error: the document is invalid
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.
Message
[BR-AE-07] In a Document level charge (BG-21) where the Document level charge VAT category code (BT-102) is "Reverse charge" the Document level charge VAT rate (BT-103) shall be 0 (zero).
Context
//ram:SpecifiedTradeAllowanceCharge[ram:ChargeIndicator/udt:Indicator='true']/ram:CategoryTradeTax[ram:CategoryCode = 'AE']
Test
ram:RateApplicablePercent = 0
Checked with Factur-X / ZUGFeRD BASIC