Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingConfiguration.cs
===================================================================
diff -u -r9e196d166be69221bf9cc0285136d20a7310fac8 -r59c7d166234297687e0b709fb5112836f22b32e5
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingConfiguration.cs	(.../HydraRingConfiguration.cs)	(revision 9e196d166be69221bf9cc0285136d20a7310fac8)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingConfiguration.cs	(.../HydraRingConfiguration.cs)	(revision 59c7d166234297687e0b709fb5112836f22b32e5)
@@ -33,23 +33,14 @@
     public class HydraRingConfiguration
     {
         /// <summary>
-        /// Creates a new instance of the <see cref="HydraRingConfiguration"/> class.
-        /// </summary>
-        public HydraRingConfiguration()
-        {
-            HydraRingTimeIntegrationSchemeType = HydraRingTimeIntegrationSchemeType.Undefined;
-            HydraRingUncertaintiesType = HydraRingUncertaintiesType.Undefined;
-        }
-
-        /// <summary>
         /// Gets or sets the <see cref="HydraRingTimeIntegrationSchemeType"/>.
         /// </summary>
-        public HydraRingTimeIntegrationSchemeType HydraRingTimeIntegrationSchemeType { get; set; }
+        public HydraRingTimeIntegrationSchemeType? HydraRingTimeIntegrationSchemeType { get; set; }
 
         /// <summary>
         /// Gets or sets the <see cref="HydraRingUncertaintiesType"/>.
         /// </summary>
-        public HydraRingUncertaintiesType HydraRingUncertaintiesType { get; set; }
+        public HydraRingUncertaintiesType? HydraRingUncertaintiesType { get; set; }
 
         /// <summary>
         /// Gets or sets the <see cref="HydraulicBoundaryLocation"/>.
@@ -80,10 +71,10 @@
                 new OrderedDictionary
                 {
                     {
-                        "TimeIntegrationSchemeID", HydraRingTimeIntegrationSchemeType != HydraRingTimeIntegrationSchemeType.Undefined ? (int?) HydraRingTimeIntegrationSchemeType : null
+                        "TimeIntegrationSchemeID", HydraRingTimeIntegrationSchemeType != null ? (int?) HydraRingTimeIntegrationSchemeType : null
                     },
                     {
-                        "UncertaintiesID", HydraRingUncertaintiesType != HydraRingUncertaintiesType.Undefined ? (int?) HydraRingUncertaintiesType : null
+                        "UncertaintiesID", HydraRingUncertaintiesType != null ? (int?) HydraRingUncertaintiesType : null
                     },
                     {
                         "DataSetName", "WTI 2017" // Fixed: use the WTI 2017 set of station locations
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingTimeIntegrationSchemeType.cs
===================================================================
diff -u -r9e196d166be69221bf9cc0285136d20a7310fac8 -r59c7d166234297687e0b709fb5112836f22b32e5
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingTimeIntegrationSchemeType.cs	(.../HydraRingTimeIntegrationSchemeType.cs)	(revision 9e196d166be69221bf9cc0285136d20a7310fac8)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingTimeIntegrationSchemeType.cs	(.../HydraRingTimeIntegrationSchemeType.cs)	(revision 59c7d166234297687e0b709fb5112836f22b32e5)
@@ -25,11 +25,10 @@
     /// Enumeration that defines the time integration scheme types supported by Hydra-Ring.
     /// </summary>
     /// <remarks>
-    /// Except for <see cref="Undefined"/>, the integer values correspond to time integration scheme ids defined within Hydra-Ring.
+    /// The integer values correspond to time integration scheme ids defined within Hydra-Ring.
     /// </remarks>
     public enum HydraRingTimeIntegrationSchemeType
     {
-        Undefined = -1,
         FBC = 1,
         APT = 2,
         NTI = 3
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingUncertaintiesType.cs
===================================================================
diff -u -r9e196d166be69221bf9cc0285136d20a7310fac8 -r59c7d166234297687e0b709fb5112836f22b32e5
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingUncertaintiesType.cs	(.../HydraRingUncertaintiesType.cs)	(revision 9e196d166be69221bf9cc0285136d20a7310fac8)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/HydraRingUncertaintiesType.cs	(.../HydraRingUncertaintiesType.cs)	(revision 59c7d166234297687e0b709fb5112836f22b32e5)
@@ -25,11 +25,10 @@
     /// Enumeration that defines the uncertainties types supported by Hydra-Ring.
     /// </summary>
     /// <remarks>
-    /// Except for <see cref="Undefined"/>, the integer values correspond to uncertainties ids defined within Hydra-Ring.
+    /// The integer values correspond to uncertainties ids defined within Hydra-Ring.
     /// </remarks>
     public enum HydraRingUncertaintiesType
     {
-        Undefined = -1,
         None = 0, // "No uncertainties"
         All = 1, // "All uncertainties"
         Model = 2, // "Only model uncertainties"
Index: Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/HydraRingTimeIntegrationSchemeTypeTest.cs
===================================================================
diff -u -r9e196d166be69221bf9cc0285136d20a7310fac8 -r59c7d166234297687e0b709fb5112836f22b32e5
--- Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/HydraRingTimeIntegrationSchemeTypeTest.cs	(.../HydraRingTimeIntegrationSchemeTypeTest.cs)	(revision 9e196d166be69221bf9cc0285136d20a7310fac8)
+++ Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/HydraRingTimeIntegrationSchemeTypeTest.cs	(.../HydraRingTimeIntegrationSchemeTypeTest.cs)	(revision 59c7d166234297687e0b709fb5112836f22b32e5)
@@ -28,15 +28,14 @@
     public class HydraRingTimeIntegrationSchemeTypeTest
     {
         [Test]
-        public void Values_HasFour()
+        public void Values_HasThree()
         {
-            Assert.AreEqual(4, Enum.GetValues(typeof(HydraRingTimeIntegrationSchemeType)).Length);
+            Assert.AreEqual(3, Enum.GetValues(typeof(HydraRingTimeIntegrationSchemeType)).Length);
         }
 
         [Test]
         public void ConvertToInteger_ForAllValues_ReturnsExpectedInteger()
         {
-            Assert.AreEqual(-1, (int) HydraRingTimeIntegrationSchemeType.Undefined);
             Assert.AreEqual(1, (int) HydraRingTimeIntegrationSchemeType.FBC);
             Assert.AreEqual(2, (int) HydraRingTimeIntegrationSchemeType.APT);
             Assert.AreEqual(3, (int) HydraRingTimeIntegrationSchemeType.NTI);
Index: Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/HydraRingUncertaintiesTypeTest.cs
===================================================================
diff -u -r9e196d166be69221bf9cc0285136d20a7310fac8 -r59c7d166234297687e0b709fb5112836f22b32e5
--- Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/HydraRingUncertaintiesTypeTest.cs	(.../HydraRingUncertaintiesTypeTest.cs)	(revision 9e196d166be69221bf9cc0285136d20a7310fac8)
+++ Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/HydraRingUncertaintiesTypeTest.cs	(.../HydraRingUncertaintiesTypeTest.cs)	(revision 59c7d166234297687e0b709fb5112836f22b32e5)
@@ -28,15 +28,14 @@
     public class HydraRingUncertaintiesTypeTest
     {
         [Test]
-        public void Values_HasFive()
+        public void Values_HasFour()
         {
-            Assert.AreEqual(5, Enum.GetValues(typeof(HydraRingUncertaintiesType)).Length);
+            Assert.AreEqual(4, Enum.GetValues(typeof(HydraRingUncertaintiesType)).Length);
         }
 
         [Test]
         public void ConvertToInteger_ForAllValues_ReturnsExpectedInteger()
         {
-            Assert.AreEqual(-1, (int) HydraRingUncertaintiesType.Undefined);
             Assert.AreEqual(0, (int) HydraRingUncertaintiesType.None);
             Assert.AreEqual(1, (int) HydraRingUncertaintiesType.All);
             Assert.AreEqual(2, (int) HydraRingUncertaintiesType.Model);