In a Document level allowance (BG-20) where the Document level allowance VAT category code (BT-95) is "IGIC" the Document level allowance VAT rate (BT-96) shall be 0 (zero) or greater than zero.
cac:AllowanceCharge[cbc:ChargeIndicator=false()]/cac:TaxCategory[normalize-space(cbc:ID)='L'][cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT'](cbc:Percent) >= 0