Minor enhancements for version 2.3 of specification

Core/Address.cs

@@ -8,6 +8,8 @@
 
 using System;
 using System.Collections.Generic;
+using System.Net;
+using System.Xml.Linq;
 
 namespace Codecrete.SwissQRBill.Generator
 {
@@ -20,6 +22,10 @@ namespace Codecrete.SwissQRBill.Generator
     /// If fields of both types are set, the address type becomes <i>conflicting</i>.
     /// Name and country code must always be set unless all fields are empty.
     /// </para>
+    /// <para>
+    /// Banks will no longer accept payments using the combined address elements starting November 21, 2025.
+    /// Therefore, it is recommended to use structured addresses immediately.
+    /// </para>
     /// </summary>
     public sealed class Address : IEquatable<Address>
     {
@@ -35,6 +41,9 @@ public enum AddressType
             Undetermined,
             /// <summary>
             /// Structured address
+            /// <para>
+            /// This is a temporary type and not suitable for a valid payment.
+            /// </para>
             /// </summary>
             Structured,
             /// <summary>
@@ -43,6 +52,9 @@ public enum AddressType
             CombinedElements,
             /// <summary>
             /// Conflicting
+            /// <para>
+            /// This a an invalid type and will prevent the generation of a QR bill.
+            /// </para>
             /// </summary>
             Conflicting
         }
@@ -87,7 +99,8 @@ private void ChangeType(AddressType desiredType)
         /// <see cref="AddressType.Structured"/>, in which case it becomes <see cref="AddressType.Conflicting"/>.
         /// </para>
         /// <para>
-        /// This field is only used for combined elements addresses and is optional.
+        /// This field is only used for combined address elements and is optional.
+        /// Starting November 25, 2025, banks will no longer accept payments using combined address elements.
         /// </para>
         /// </summary>
         /// <value>The address line 1.</value>
@@ -113,7 +126,8 @@ public string AddressLine1
         /// <see cref="AddressType.Structured"/>, in which case it becomes <see cref="AddressType.Conflicting"/>.
         /// </para>
         /// <para>
-        /// This field is only used for combined elements addresses. For this type, it's mandatory.
+        /// This field is only used for combined address elements. For this type, it is mandatory.
+        /// Starting November 25, 2025, banks will no longer accept payments using combined address elements.
         /// </para>
         /// </summary>
         /// <value>The address line 2.</value>

Core/Payments.cs

@@ -351,6 +351,11 @@ public static bool IsValidQrReference(string reference)
                 return false;
             }
 
+            if ("000000000000000000000000000" == reference)
+            {
+                return false;
+            }
+
             return CalculateMod10(reference) == 0;
         }
 

CoreTest/QRReferenceTest.cs

@@ -72,6 +72,13 @@ public void CreateQRReferenceWithWhitespace()
                     Payments.CreateQRReference("  12 3456 "));
         }
 
+        [Fact]
+        public void AllZeroes_IsInvalid()
+        {
+            Assert.False(Payments.IsValidQrReference("000000000000000000000000000"));
+            Assert.False(Payments.IsValidQrReference("00 00000 00000 00000 00000 00000"));
+        }
+
         [Fact]
         public void RawReferenceWithInvalidCharacters()
         {