At most one FC tax registration

Error FX-SCH-A-000034 Factur-X

Element variant 'ram:SpecifiedTaxRegistration[ram:ID/@schemeID="FC"]' may occur at maximum 1 times.

Mandatory rule: As long as it is violated, the invoice is invalid and will be rejected by validators.
What is wrong

In SellerTradeParty, SpecifiedTaxRegistration with an ID whose schemeID is FC occurs more than once.

What the rule means

At most one tax registration is allowed for the FC designation. Multiple such entries repeat this designation in the seller’s record.

Please provide no more than one tax registration with `FC`

The seller’s details contain the tax registration with FC more than once. You can make this entry unambiguous.

What to do
  1. Find SpecifiedTaxRegistration with ID and schemeID="FC" in SellerTradeParty.
  2. Remove duplicate entries so that this entry occurs no more than once.
  3. Generate the invoice again and validate it.
What it looks like
✗ Triggers the message 
<ram:SellerTradeParty>
  <ram:SpecifiedTaxRegistration>
    <ram:ID schemeID="FC">A</ram:ID>
  </ram:SpecifiedTaxRegistration>
  <ram:SpecifiedTaxRegistration>
    <ram:ID schemeID="FC">B</ram:ID>
  </ram:SpecifiedTaxRegistration>
</ram:SellerTradeParty>
✓ Correct 
<ram:SellerTradeParty>
  <ram:SpecifiedTaxRegistration>
    <ram:ID schemeID="FC">A</ram:ID>
  </ram:SpecifiedTaxRegistration>
</ram:SellerTradeParty>
Technical details

The check counts the direct SpecifiedTaxRegistration elements whose child ID has a schemeID attribute with the value FC.

Where the rule applies

The rule applies to the seller’s tax registrations in SellerTradeParty.

Context (rule/@context)
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ ram:SellerTradeParty
Test expression (assert/@test)
count(ram:SpecifiedTaxRegistration[ram:ID/@schemeID="FC"])<=1