# BT-16 Despatch advice reference

Reference to the despatch advice that announced the shipment before invoicing.

## Quick answer

Reference to the despatch advice that announced the shipment before invoicing.

> **Invoice basics**: Core document identifiers, dates, process identifiers, and high-level invoice context.

## In plain language

Reference to the despatch advice that announced the shipment before invoicing.

Reference to the despatch advice that announced the shipment before invoicing.

This field is useful in logistics-heavy flows where the buyer checks invoice, shipment, and receipt documents together.

## What you usually enter here

Despatch or shipment reference

Typical valid values include: DES-2026-44

Optional according to EN 16931-1.

## What goes wrong often

Avoid values like: , AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

## Examples in context

This field is useful in logistics-heavy flows where the buyer checks invoice, shipment, and receipt documents together.

Optional according to EN 16931-1.

## Valid Examples

- DES-2026-44

## Invalid Examples

- AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

## Related Fields

This field is useful in logistics-heavy flows where the buyer checks invoice, shipment, and receipt documents together.

- [BT-15 Receiving advice reference](/resources/xrechnung/bt-15-receiving-advice-reference)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-16

### Data Type:
text

### Cardinality:
0..1

### Requirement:
Optional

### Max Length:
50 characters

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:DespatchDocumentReference/cbc:ID
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeDelivery/ram:DespatchAdviceReferencedDocument/ram:IssuerAssignedID
```

## Why the standard cares about this field

### Business Context
This field is useful in logistics-heavy flows where the buyer checks invoice, shipment, and receipt documents together.

### Legal Requirement
Optional according to EN 16931-1.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [Invoice Converter](/pdf-to-xrechnung)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)