# DE-R-T02

Source: https://xmlvalid.com/rules/DE-R-T02

> If both supplier and customer are located in Germany, BT-124 "External document location" must contain an absolute URL with valid scheme.

- Level: warning
- Rule sets: Peppol BIS Billing 3.0 rules 3.0.21
- Context: `(/ubl-invoice:Invoice/cac:AdditionalDocumentReference/cac:Attachment/cac:ExternalReference | /ubl-creditnote:CreditNote/cac:AdditionalDocumentReference/cac:Attachment/cac:ExternalReference)[$supplierCountryIsDE and $customerCountryIsDE]`
- Test: `matches(cbc:URI, $XR-URL-REGEX)`

Validate a document against these rules: https://xmlvalid.com/validate