EN16931 1.3.16 · UBL / CII · Severity: ERROR
An Invoice shall have an Invoice number (BT-1)
Every invoice must carry a unique sequential identifier (BT-1) assigned by the seller.
- Rule ID & Severity
BR-02· ERROR- Standard & Scope
- EN16931 1.3.16 · UBL / CII
- XPath Condition
exists(cbc:ID[normalize-space(.) != ""])- Target XML Path
cbc:ID
Find the source field
cbc:ID
Match namespace URI and element name, not a particular prefix spelling. The validator reports the full expanded-name source path when the published rule supplies a location.
Common causes
- Draft invoice was exported before a document number was assigned.
- Wrong XML field was mapped for the invoice number.
Invalid and corrected fragments
<cbc:ID></cbc:ID>
<cbc:ID>INV-2026-1048</cbc:ID>
Export the finalized invoice number into the root cbc:ID (UBL) or rsm:ExchangedDocument/ram:ID (CII) element.
Open BR-02 in en16931-validator →
Verify the whole document
These are fragments, not complete invoices. The exact rule is exercised by synthetic mutation tests against the stated package. Correcting one field does not prove conformance; run the full selected validator again. Published messages and severity remain authoritative.
Explanation record: 2026-10-14 · Local WebAssembly / SaxonJS validation. No invoice-derived report is published as a search page.