{
  "id": "UBL-SR-31",
  "country": "EU",
  "syntax": "ubl",
  "group": "syntax",
  "severity": "fatal",
  "severity_note": "fatal, from the Flag column of the Peppol BIS Billing 3.0 UBL rules index retrieved 2026-10-18.",
  "spec": "Peppol BIS Billing 3.0, May 2026 release, EN 16931 model bound to UBL",
  "statement": "Document level charge reason shall occur maximum once",
  "statement_lang": "en",
  "context": "cac:AllowanceCharge[cbc:ChargeIndicator = true()]",
  "test": "(count(cbc:AllowanceChargeReason) <= 1)",
  "meaning": "The document level charge reason shall occur at most once. The statement has no period and says shall. It is 53 characters. The flag is fatal. The context is an allowance charge whose charge indicator is true. That comparison writes = with a space on each side. The published test counts cbc:AllowanceChargeReason. That test string is the same as UBL-SR-30. The count comparison has a space before <= and a space after it.",
  "fix": "On a document-level charge, send at most one charge reason.",
  "example_fail": "A document-level charge has two charge reasons.",
  "example_pass": "A document-level charge has one charge reason, or none.",
  "example_note": "Illustration of the condition in the official statement. Not an example published by the source.",
  "source_url": "https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-SR-31/",
  "source_retrieved": "2026-10-18",
  "last_verified": "2026-10-18"
}