Index: Riskeer/MacroStabilityInwards/src/Riskeer.MacroStabilityInwards.IO/Factories/MacroStabilityInwardsExportRegistry.cs
===================================================================
diff -u -rc5e749d6f198b9edd2d35bfd137ee8c5dc6b82a8 -r6234fe337ff6b2a02024a021bf29cc28b90cb6d3
--- Riskeer/MacroStabilityInwards/src/Riskeer.MacroStabilityInwards.IO/Factories/MacroStabilityInwardsExportRegistry.cs	(.../MacroStabilityInwardsExportRegistry.cs)	(revision c5e749d6f198b9edd2d35bfd137ee8c5dc6b82a8)
+++ Riskeer/MacroStabilityInwards/src/Riskeer.MacroStabilityInwards.IO/Factories/MacroStabilityInwardsExportRegistry.cs	(.../MacroStabilityInwardsExportRegistry.cs)	(revision 6234fe337ff6b2a02024a021bf29cc28b90cb6d3)
@@ -35,6 +35,7 @@
         private readonly Dictionary<MacroStabilityInwardsSoilLayer2D, string> soils;
         private readonly Dictionary<MacroStabilityInwardsExportStageType, string> geometries;
         private readonly Dictionary<MacroStabilityInwardsExportStageType, Dictionary<MacroStabilityInwardsSoilLayer2D, string>> geometryLayers;
+        private readonly Dictionary<MacroStabilityInwardsExportStageType, string> soilLayers;
 
         /// <summary>
         /// Creates a new instance of <see cref="MacroStabilityInwardsExportRegistry"/>.
@@ -45,6 +46,7 @@
             soils = new Dictionary<MacroStabilityInwardsSoilLayer2D, string>();
             geometries = new Dictionary<MacroStabilityInwardsExportStageType, string>();
             geometryLayers = new Dictionary<MacroStabilityInwardsExportStageType, Dictionary<MacroStabilityInwardsSoilLayer2D, string>>();
+            soilLayers = new Dictionary<MacroStabilityInwardsExportStageType, string>();
         }
 
         /// <summary>
@@ -68,6 +70,11 @@
         public IReadOnlyDictionary<MacroStabilityInwardsExportStageType, Dictionary<MacroStabilityInwardsSoilLayer2D, string>> GeometryLayers => geometryLayers;
 
         /// <summary>
+        /// Gets the soil layers and their unique identifiers.
+        /// </summary>
+        public IReadOnlyDictionary<MacroStabilityInwardsExportStageType, string> SoilLayers => soilLayers;
+
+        /// <summary>
         /// Adds calculation settings to the registry.
         /// </summary>
         /// <param name="stageType">The <see cref="MacroStabilityInwardsExportStageType"/>
@@ -143,6 +150,21 @@
         }
 
         /// <summary>
+        /// Adds a soil layer to the register.
+        /// </summary>
+        /// <param name="stageType">The <see cref="MacroStabilityInwardsExportStageType"/>
+        /// to register the soil layer for.</param>
+        /// <param name="id">The id of the settings.</param>
+        /// <exception cref="InvalidEnumArgumentException">Thrown when <paramref name="stageType"/>
+        /// has an invalid value.</exception>
+        public void AddSoilLayer(MacroStabilityInwardsExportStageType stageType, string id)
+        {
+            ValidateStageType(stageType);
+
+            soilLayers.Add(stageType, id);
+        }
+
+        /// <summary>
         /// Validates the <see cref="MacroStabilityInwardsExportStageType"/>.
         /// </summary>
         /// <param name="stageType">The stage type to validate.</param>
Index: Riskeer/MacroStabilityInwards/test/Riskeer.MacroStabilityInwards.IO.Test/Factories/MacroStabilityInwardsExportRegistryTest.cs
===================================================================
diff -u -r76b0441378930f0e6052aa3e65332dc23fe4b0be -r6234fe337ff6b2a02024a021bf29cc28b90cb6d3
--- Riskeer/MacroStabilityInwards/test/Riskeer.MacroStabilityInwards.IO.Test/Factories/MacroStabilityInwardsExportRegistryTest.cs	(.../MacroStabilityInwardsExportRegistryTest.cs)	(revision 76b0441378930f0e6052aa3e65332dc23fe4b0be)
+++ Riskeer/MacroStabilityInwards/test/Riskeer.MacroStabilityInwards.IO.Test/Factories/MacroStabilityInwardsExportRegistryTest.cs	(.../MacroStabilityInwardsExportRegistryTest.cs)	(revision 6234fe337ff6b2a02024a021bf29cc28b90cb6d3)
@@ -45,6 +45,7 @@
             CollectionAssert.IsEmpty(registry.Soils);
             CollectionAssert.IsEmpty(registry.Geometries);
             CollectionAssert.IsEmpty(registry.GeometryLayers);
+            CollectionAssert.IsEmpty(registry.SoilLayers);
         }
 
         [Test]
@@ -75,9 +76,9 @@
 
             // Assert
             Assert.AreEqual(1, registry.Settings.Count);
-            KeyValuePair<MacroStabilityInwardsExportStageType, string> storedSettings = registry.Settings.Single();
-            Assert.AreEqual(stageType, storedSettings.Key);
-            Assert.AreEqual(id, storedSettings.Value);
+            KeyValuePair<MacroStabilityInwardsExportStageType, string> registeredSettings = registry.Settings.Single();
+            Assert.AreEqual(stageType, registeredSettings.Key);
+            Assert.AreEqual(id, registeredSettings.Value);
         }
 
         [Test]
@@ -129,7 +130,7 @@
         }
 
         [Test]
-        public void AddGeometry_WithGeometry_AddsSettings()
+        public void AddGeometry_WithGeometry_AddsGeometry()
         {
             // Setup
             var registry = new MacroStabilityInwardsExportRegistry();
@@ -141,9 +142,9 @@
 
             // Assert
             Assert.AreEqual(1, registry.Geometries.Count);
-            KeyValuePair<MacroStabilityInwardsExportStageType, string> storedGeometry = registry.Geometries.Single();
-            Assert.AreEqual(stageType, storedGeometry.Key);
-            Assert.AreEqual(id, storedGeometry.Value);
+            KeyValuePair<MacroStabilityInwardsExportStageType, string> registeredGeometry = registry.Geometries.Single();
+            Assert.AreEqual(stageType, registeredGeometry.Key);
+            Assert.AreEqual(id, registeredGeometry.Value);
         }
 
         [Test]
@@ -238,5 +239,38 @@
             Assert.AreSame(geometryLayer2, registeredGeometry2.Key);
             Assert.AreEqual(id2, registeredGeometry2.Value);
         }
+
+        [Test]
+        public void AddSoilLayer_InvalidStageType_ThrowsInvalidEnumArgumentException()
+        {
+            // Setup
+            var registry = new MacroStabilityInwardsExportRegistry();
+            const MacroStabilityInwardsExportStageType stageType = (MacroStabilityInwardsExportStageType)99;
+
+            // Call
+            void Call() => registry.AddSoilLayer(stageType, "1");
+
+            // Assert
+            string expectedMessage = $"The value of argument '{nameof(stageType)}' ({stageType}) is invalid for Enum type '{nameof(MacroStabilityInwardsExportStageType)}'.";
+            TestHelper.AssertThrowsArgumentExceptionAndTestMessage<InvalidEnumArgumentException>(Call, expectedMessage);
+        }
+
+        [Test]
+        public void AddSoilLayer_WithSoilLayer_AddsSoilLayer()
+        {
+            // Setup
+            var registry = new MacroStabilityInwardsExportRegistry();
+            var stageType = new Random(21).NextEnumValue<MacroStabilityInwardsExportStageType>();
+            const string id = "1";
+
+            // Call
+            registry.AddSoilLayer(stageType, id);
+
+            // Assert
+            Assert.AreEqual(1, registry.SoilLayers.Count);
+            KeyValuePair<MacroStabilityInwardsExportStageType, string> registeredSoilLayers = registry.SoilLayers.Single();
+            Assert.AreEqual(stageType, registeredSoilLayers.Key);
+            Assert.AreEqual(id, registeredSoilLayers.Value);
+        }
     }
 }
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