diff --git a/Directory.Build.props b/Directory.Build.props
index 52332b7..41e8f40 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -9,7 +9,7 @@
 	<Product>Choice generator</Product>
 	<Company>ALTA Software llc.</Company>
 	<Copyright>Copyright © 2024 ALTA Software llc.</Copyright>
-	<Version>1.2.3</Version>
+	<Version>1.3.0</Version>
   </PropertyGroup>
 
   <PropertyGroup>
diff --git a/src/AltaSoft.Choice.Generator/Executor.cs b/src/AltaSoft.Choice.Generator/Executor.cs
index d284c9a..4ec1948 100644
--- a/src/AltaSoft.Choice.Generator/Executor.cs
+++ b/src/AltaSoft.Choice.Generator/Executor.cs
@@ -115,6 +115,8 @@ private static SourceCodeBuilder Process(INamedTypeSymbol typeSymbol, List<IProp
                 sb.Append("[XmlElement(\"").Append(p.XmlNameValue).AppendLine("\")]");
             }
 
+            sb.AppendLine("[ChoiceProperty]");
+
             sb.Append("public partial ").Append(p.TypeName).Append("? ").Append(p.Name)
                 .OpenBracket();
 
diff --git a/src/AltaSoft.Choice/ChoicePropertyAttribute.cs b/src/AltaSoft.Choice/ChoicePropertyAttribute.cs
new file mode 100644
index 0000000..8b40eb3
--- /dev/null
+++ b/src/AltaSoft.Choice/ChoicePropertyAttribute.cs
@@ -0,0 +1,9 @@
+using System;
+
+namespace AltaSoft.Choice;
+
+/// <summary>
+/// Represents the attribute used to mark a property as a choice property.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property)]
+public sealed class ChoicePropertyAttribute : Attribute;
diff --git a/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldGenerateAllMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs b/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldGenerateAllMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs
index e4118cb..758cb24 100644
--- a/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldGenerateAllMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs
+++ b/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldGenerateAllMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs
@@ -49,6 +49,7 @@ public Authorisation1Choice()
     /// </summary>
     [DisallowNull]
     [XmlElement("Code")]
+    [ChoiceProperty]
     public partial TestNamespace.OtherNamespace.Authorisation1Code? Code
     {
         get => _code;
@@ -67,6 +68,7 @@ public partial TestNamespace.OtherNamespace.Authorisation1Code? Code
     /// </summary>
     [DisallowNull]
     [XmlElement("Proprietary")]
+    [ChoiceProperty]
     public partial string? Proprietary
     {
         get => _proprietary;
diff --git a/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldNotGenerateImplicitMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs b/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldNotGenerateImplicitMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs
index 0d1bcac..a943f9a 100644
--- a/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldNotGenerateImplicitMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs
+++ b/tests/AltaSoft.Choice.Generator.SnapshotTests/Snapshots/ChoiceGeneratorTest.ChoiceTypeShouldNotGenerateImplicitMethodsAndCompileCorrectly#Authorisation1Choice.g.verified.cs
@@ -49,6 +49,7 @@ public Authorisation1Choice()
     /// </summary>
     [DisallowNull]
     [XmlElement("Code")]
+    [ChoiceProperty]
     public partial string? Code
     {
         get => _code;
@@ -67,6 +68,7 @@ public partial string? Code
     /// </summary>
     [DisallowNull]
     [XmlElement("Proprietary")]
+    [ChoiceProperty]
     public partial TestNamespace.OtherNamespace.Authorisation1Code? Proprietary
     {
         get => _proprietary;