# UBL-SR-52

Quoted from a public specification. This page is not a validator, and it is not tax, legal, or accounting advice.

- Country: EU
- Syntax: UBL
- Severity: fatal
- Statement language: en
- Last verified: 2026-10-18

## Official statement

> Document reference shall occur maximum once

Source: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-SR-52/

Peppol BIS Billing 3.0, May 2026 release, EN 16931 model bound to UBL

Severity note: fatal, from the Flag column of the Peppol BIS Billing 3.0 UBL rules index retrieved 2026-10-18.

## Plain-language reading

The document reference shall occur at most once. The statement has no period and says shall. It is 43 characters. The flag is fatal. The context is an invoice line or a credit note line. The published test does not wrap the count in parentheses. It counts the document reference. The count comparison has a space before <= and a space after it.

## What to change

Send at most one document reference on a line.

## Illustration

Illustration of the condition in the official statement. Not an example published by the source.

**Fails the stated condition.** An invoice line has two document references.

**Passes the stated condition.** An invoice line has one document reference, or none.

## Published context and test

Copied from the source. Not reimplemented on this page.

```
cac:InvoiceLine | cac:CreditNoteLine
```

```
count(cac:DocumentReference) <= 1
```

[All rule notes](https://einvoicegoblin.com/rules/index.md) · [JSON](https://einvoicegoblin.com/rules/UBL-SR-52.json) · [HTML](https://einvoicegoblin.com/rules/UBL-SR-52/) · [llms.txt](https://einvoicegoblin.com/llms.txt) · [Invoice page](https://einvoicegoblin.com/) · [Privacy](https://einvoicegoblin.com/privacy.html)