# BR-DE-15

Source: https://xmlvalid.com/rules/BR-DE-15

> Das Element "Buyer reference" (BT-10) muss übermittelt werden.

- Level: error
- Rule sets: XRechnung 3.0 rules (UBL) 2.6.0
- Context: `/ubl:Invoice | /cn:CreditNote`
- Test: `cbc:BuyerReference[boolean(normalize-space(.))]`

> Das Element "Buyer reference" (BT-10) muss übermittelt werden.

- Level: error
- Rule sets: XRechnung 3.0 rules (CII) 2.6.0
- Context: `/rsm:CrossIndustryInvoice`
- Test: `rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:BuyerReference[boolean(normalize-space(.))]`

## Why it fails

- An XRechnung has no `cbc:BuyerReference` (`ram:BuyerReference` in CII). German public buyers use it for the Leitweg-ID.

## How to fix it

- Put the buyer's Leitweg-ID, or the reference the buyer gave you, in BT-10.

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