# UBL-CR-673: Remove DocumentDescription from the invoiced object reference

Fatal: EN 16931 does not allow `cbc:DocumentDescription` in the invoiced object reference. The document is invalid until you remove it.

- Layer: EN 16931
- Severity: fatal (the document is invalid)
- Topics: Process and references
- Official definition: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-CR-673/
- Explanation last updated: 2026-09-29

## The short answer

`UBL-CR-673` is a fatal rule raised when the invoiced object reference, a `cac:AdditionalDocumentReference` with `cbc:DocumentTypeCode` `130`, has a `cbc:DocumentDescription`. Only supporting documents (BG-24) carry a description, so remove it here.

The document is invalid while the element is there: the EN 16931 layer fails with this rule, and a receiver can refuse the document.

## What the rule checks

The rule looks at every `cac:AdditionalDocumentReference` with `cbc:DocumentTypeCode` `130`, the invoiced object identifier (BT-18), and checks whether it has a `cbc:DocumentDescription`. Supporting documents, without code `130`, may carry one (BT-123).

It runs once against the whole document, so it is reported once however many times the document has the element, and the finding points at the document root rather than at the element: look for `cac:AdditionalDocumentReference/cbc:DocumentDescription` in the XML.

| Term | Meaning | UBL element |
|---|---|---|
| - | DocumentDescription (BT-123 on a supporting document, not on the invoiced object) | `cac:AdditionalDocumentReference/cbc:DocumentDescription` |
| BT-18 | Invoiced object reference | `cac:AdditionalDocumentReference` |

## How an integration ends up here

Possible causes, from the shape of the rule rather than from measured usage:

- The source system holds the value, and the mapping writes it because UBL 2.1 has a place for it.
- A general UBL 2.1 library writes every element and attribute it has a value for, whether or not EN 16931 uses it.
- A mapping built for another UBL-based document, such as an order, a despatch advice or a national profile, is reused for Peppol BIS Billing.

## How to fix it

1. Remove `cbc:DocumentDescription` from the reference with `cbc:DocumentTypeCode` `130`.
2. Keep the identifier and its scheme (BT-18, BT-18-1); a description belongs to a supporting document (BT-123).
3. Validate again: the document is valid once it is gone.

## Before and after

These are fragments, not complete documents. The complete synthetic documents they come from are linked below.

Fragment of the invoice with the error: DocumentDescription in the invoiced object reference

```xml
<cac:AdditionalDocumentReference>
  <cbc:ID schemeID="AAB">OBJECT-001</cbc:ID>
  <cbc:DocumentTypeCode>130</cbc:DocumentTypeCode>
  <cbc:DocumentDescription>Meter reading</cbc:DocumentDescription>
</cac:AdditionalDocumentReference>
```

Fragment of the corrected invoice: the same lines without it

```xml
<cac:AdditionalDocumentReference>
  <cbc:ID schemeID="AAB">OBJECT-001</cbc:ID>
  <cbc:DocumentTypeCode>130</cbc:DocumentTypeCode>
</cac:AdditionalDocumentReference>
```

The invoice with the error has `<cbc:DocumentDescription>Meter reading</cbc:DocumentDescription>` in the invoiced object reference, and the corrected invoice is the same document without it. It fails the EN 16931 layer with this rule alone, and every other layer passes.

### What the validator reported

- The failing invoice reports **UBL-CR-673**. The corrected document passes every layer with no findings.
  - [Download the failing XML](https://ironfang.com/finance/rule-examples/UBL-CR-673-invalid.xml)
  - [Download the corrected XML](https://ironfang.com/finance/rule-examples/syntax-invoice-complete.xml)

Recorded on phive 12.1.0 / phive-rules-peppol 4.5.6 / Saxon-HE 12.10, the engine behind the free validator, using synthetic data. A recorded result is regression evidence for these documents; it is not a certification.

## Where it applies

- Applies to UBL `Invoice` and `CreditNote` alike; the recorded example is an invoice.
- The error comes from the EN 16931 layer's rules for the UBL syntax. In the recorded example the schema layer passes: the element is valid UBL 2.1 and is only outside the EN 16931 model.

## Related rules

- [UBL-CR-666: Attachment in the invoiced object reference](https://ironfang.com/docs/finance/rules/UBL-CR-666.md)

## Scope and source

Written for Peppol BIS Billing 3.0.21 (May 2026), EN 16931 1.3.16, as applied to UBL 2.1 Invoice and CreditNote documents. Other profiles, syntaxes and releases can define this identifier differently. Guidance version 2026-09-29.1: source checked 2026-09-29, explanation last updated 2026-09-29.

[The official definition of UBL-CR-673](https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-CR-673/) carries the normative wording and test. This page is our explanation of it, not a copy.

Guidance does not change the engine verdict. Fixing this finding does not mean the document passes every layer, and validation does not certify legal or tax compliance or transmit a document over Peppol.

## Links

- [This rule as a web page](https://ironfang.com/docs/finance/rules/UBL-CR-673)
- [Free Peppol invoice validator](https://ironfang.com/tools/peppol-validator)
- [Rule index](https://ironfang.com/docs/finance/rules.md)
- [Ironfang Finance API docs](https://ironfang.com/docs/finance)
- The same rule is available to MCP clients as the tool `finance.rule.get` on https://mcp.ironfang.com/mcp