Only one project reference is allowed on document level

Only one project reference (ibt-011) is allowed on document level.

Fails

<Invoice>
  <cac:ProjectReference>…</cac:ProjectReference>
  <cac:ProjectReference>…</cac:ProjectReference>
</Invoice>

Keep a single cac:ProjectReference here and delete the duplicates. If both values matter, one of them belongs in a different field.

Schematron

Context

/ubl:Invoice | /cn:CreditNote

Test

(count(cac:ProjectReference) <= 1) and (count(cac:AdditionalDocumentReference[cbc:DocumentTypeCode='50']) <= 1)

Official text: Only one project reference (ibt-011) is allowed on document level.

Official · PINT shared rules. Severity: error. Runs on UBL XML.