1 files changed, 25 insertions, 0 deletions
diff --git a/src/mscorlib/shared/System/Runtime/Serialization/OptionalFieldAttribute.cs b/src/mscorlib/shared/System/Runtime/Serialization/OptionalFieldAttribute.cs
new file mode 100644
index 0000000000..84daa539be
--- /dev/null
+++ b/src/mscorlib/shared/System/Runtime/Serialization/OptionalFieldAttribute.cs
@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Runtime.Serialization
+{
+    [AttributeUsage(AttributeTargets.Field, Inherited = false)]
+    public sealed class OptionalFieldAttribute : Attribute
+    {
+        private int _versionAdded = 1;
+
+        public int VersionAdded
+        {
+            get { return _versionAdded; }
+            set
+            {
+                if (value < 1)
+                {
+                    throw new ArgumentException(SR.Serialization_OptionalFieldVersionValue);
+                }
+                _versionAdded = value;
+            }
+        }
+    }
+}