diff --git a/docs/Translations.md b/docs/Translations.md
index 9bc6abb..abc44a8 100644
--- a/docs/Translations.md
+++ b/docs/Translations.md
@@ -14,6 +14,11 @@
 - **Lieferdatum** – Delivery date
 
 
+**Leitweg-ID**: Routing ID
+
+**Regierungsstellen / Regierungsbehörden**: government agencies (/ government authorities)
+
+
 JetBrains Rechnung:
 
 ```text
diff --git a/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/mapper/MustangMapper.kt b/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/mapper/MustangMapper.kt
index 21e7b81..9cae491 100644
--- a/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/mapper/MustangMapper.kt
+++ b/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/mapper/MustangMapper.kt
@@ -28,7 +28,7 @@ open class MustangMapper(
         this.dueDate = map(invoice.details.dueDate)
         this.paymentTermDescription = invoice.details.paymentDescription
 
-        this.referenceNumber = invoice.customerReference
+        this.referenceNumber = invoice.customerReferenceNumber
 
         invoice.amountAdjustments?.let { adjustments ->
             this.totalPrepaidAmount = adjustments.prepaidAmounts
@@ -100,7 +100,7 @@ open class MustangMapper(
         customer = mapParty(invoice.recipient),
         items = invoice.zfItems.map { mapLineItem(it) },
 
-        customerReference = invoice.referenceNumber,
+        customerReferenceNumber = invoice.referenceNumber,
 
         amountAdjustments = mapAmountAdjustments(invoice),
 
diff --git a/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/model/Invoice.kt b/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/model/Invoice.kt
index 4d23539..da05217 100644
--- a/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/model/Invoice.kt
+++ b/e-invoice-domain/src/main/kotlin/net/codinux/invoicing/model/Invoice.kt
@@ -7,9 +7,20 @@ class Invoice(
     val items: List<InvoiceItem>,
 
     /**
-     * Unique reference number of the customer, e.g. the Leitweg-ID required by German authorities (Behörden)
+     * An identifier assigned by the Buyer used for internal routing purposes.
+     *
+     * The identifier is defined by the Buyer (e.g. contact ID, department, office id, project code), but provided by the
+     * Seller in the Invoice.
+     *
+     * In XRechnung mandatory for invoices to government agencies in Germany (B2G and G2G) to set the Leitweg-ID here.
+     *
+     * From XRechnung specification:
+     * "Anmerkung: Im Rahmen des Steuerungsprojekts eRechnung ist mit der so genannten Leitweg-ID eine Zuord-
+     * nungsmöglichkeit entwickelt worden, deren verbindliche Nutzung von Bund und mehreren Ländern vorgegeben
+     * wird. Die Leitweg-ID ist prinzipiell für Bund, Länder und Kommunen einsetzbar (B2G, G2G). Für die Darstellung
+     * der Leitweg-ID wird das in XRechnung verpflichtende Feld Buyer Reference benutzt."
      */
-    val customerReference: String? = null,
+    val customerReferenceNumber: String? = null,
 
     val amountAdjustments: AmountAdjustments? = null,