CII-SR-471
Each Specified Trade Allowance Charge (BG-20)(BG-21) shall contain a VAT category code (BT-95).
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.
//ram:SpecifiedTradeAllowanceCharge
count(ram:RateApplicablePercent) <= 1
Checked with France e-invoice (CII), XRechnung 3.0 Invoice (CII)
//ram:SpecifiedTradeAllowanceCharge
count(ram:CategoryTradeTax) <= 1
Checked with France Factur-X BASIC WL, Factur-X / ZUGFeRD BASIC WL