Manually added TimeReferenceCode

e-invoice-domain/src/main/kotlin/net/codinux/invoicing/model/codes/TimeReferenceCode.kt

@@ -0,0 +1,25 @@
+package net.codinux.invoicing.model.codes
+
+/**
+ * Subset of UNTDID 2005/ UNTDID 2475 — Event time code for field BT-8.
+ */
+enum class TimeReferenceCode(val code: Int, val description: String, val germanDescription: String) {
+
+    // UNTDID 2005
+
+    InvoiceDocumentIssueDate(3, "Invoice document issue date time", "Ausstellungsdatum des Rechnungsdokuments"),
+
+    DeliveryDate(35, "Delivery date/time, actual", "tatsächliches Lieferdatum"),
+
+    PaidToDate(432, "Paid to date", "Datum der Zahlung"),
+
+    // the specification tricks me here: While XRechnung only mentions the values from UNTDID 2005,
+    // ZUGFeRD mixes in his spec above values with these from UNTDID 2475:
+
+//    DateOfInvoice(5, "Date of invoice"),
+//
+//    DateOfDelivery(29, "Date of delivery of goods to establishments/domicile/site"),
+//
+//    PaymentDate(72, "Payment date"),
+
+}