BR-CL-24 An attachment must use one of the MIME types EN 16931 allows

"attachment": { "filename": "timesheet.pdf", "mimeCode": "application/pdf", "content": "JVBERi0xLjQK" }

{
  "rule": "BR-CL-24",
  "field": "BT-125",
  "severity": "fatal",
  "message": "The attachment on supporting document 1 declares the mime code \"application/zip\" (BT-125-1), which EN 16931 does not admit. The list has exactly 6 entries — \"application/pdf\", \"image/png\", \"image/jpeg\", \"text/csv\", \"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet\" and \"application/vnd.oasis.opendocument.spreadsheet\" — and the shortness is the point: an invoice attachment has to be openable by a receiver, without the sender's software, ten years from now, and without executing anything. That rules out archives (which can hide anything), word-processor formats with macro capability, and vector formats that carry script. A perfectly legitimate ZIP of evidence still fails.",
  "fix": "Set supportingDocuments[].attachment.mimeCode to one of the six admitted values — \"application/pdf\" is the safe default, and converting to PDF is usually easier than arguing with a receiving portal. Use externalUri (BT-124) to point at a document you cannot embed in an accepted format.",
  "example": "\"attachment\": { \"filename\": \"timesheet.pdf\", \"mimeCode\": \"application/pdf\", \"content\": \"JVBERi0xLjQK\" }",
  "xpath": "/ubl:Invoice/cac:AdditionalDocumentReference[1]/cac:Attachment/cbc:EmbeddedDocumentBinaryObject/@mimeCode",
  "docsUrl": "https://attestwire.com/rules/BR-CL-24"
}