Index: Core/Components/src/Core.Components.Gis/Theme/MapTheme.cs
===================================================================
diff -u -r2a81f01756e227d5ce93717b21b87e8a5cd5fcbb -r0360ee3f46482f5a322c28e10aa1e7f23e999c12
--- Core/Components/src/Core.Components.Gis/Theme/MapTheme.cs	(.../MapTheme.cs)	(revision 2a81f01756e227d5ce93717b21b87e8a5cd5fcbb)
+++ Core/Components/src/Core.Components.Gis/Theme/MapTheme.cs	(.../MapTheme.cs)	(revision 0360ee3f46482f5a322c28e10aa1e7f23e999c12)
@@ -26,13 +26,14 @@
 namespace Core.Components.Gis.Theme
 {
     /// <summary>
-    /// Class that contains the definition for a categorial theming of 
+    /// Class that contains the definition for a categorical theming of 
     /// map data objects.
     /// </summary>
-    public class MapTheme
+    /// <typeparam name="TCategoryTheme">The type of category theme for the categorical theming.</typeparam>
+    public class MapTheme<TCategoryTheme> where TCategoryTheme : CategoryTheme
     {
         /// <summary>
-        /// Creates a new instance of <see cref="MapTheme"/>.
+        /// Creates a new instance of <see cref="MapTheme{T}"/>.
         /// </summary>
         /// <param name="attributeName">The name of the attribute to which the theme is applicable for.</param>
         /// <param name="categoryThemes">The category themes that are applicable for the map theme.</param>
@@ -42,7 +43,7 @@
         /// <item><paramref name="attributeName"/> is null, empty or consists of only whitespace.</item>
         /// <item><paramref name="categoryThemes"/> is empty.</item>
         /// </list></exception>
-        public MapTheme(string attributeName, IEnumerable<CategoryTheme> categoryThemes)
+        public MapTheme(string attributeName, IEnumerable<TCategoryTheme> categoryThemes)
         {
             if (string.IsNullOrWhiteSpace(attributeName))
             {
@@ -71,6 +72,6 @@
         /// <summary>
         /// Gets the category themes that are applicable for the theme.
         /// </summary>
-        public IEnumerable<CategoryTheme> CategoryThemes { get; }
+        public IEnumerable<TCategoryTheme> CategoryThemes { get; }
     }
 }
\ No newline at end of file
Index: Core/Components/test/Core.Components.Gis.Test/Theme/MapThemeTest.cs
===================================================================
diff -u -r2a81f01756e227d5ce93717b21b87e8a5cd5fcbb -r0360ee3f46482f5a322c28e10aa1e7f23e999c12
--- Core/Components/test/Core.Components.Gis.Test/Theme/MapThemeTest.cs	(.../MapThemeTest.cs)	(revision 2a81f01756e227d5ce93717b21b87e8a5cd5fcbb)
+++ Core/Components/test/Core.Components.Gis.Test/Theme/MapThemeTest.cs	(.../MapThemeTest.cs)	(revision 0360ee3f46482f5a322c28e10aa1e7f23e999c12)
@@ -20,7 +20,6 @@
 // All rights reserved.
 
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using Core.Common.TestUtil;
 using Core.Components.Gis.TestUtil;
@@ -39,9 +38,9 @@
         public void Constructor_InvalidAttribute_ThrowsArgumentException(string invalidAttributeName)
         {
             // Call
-            TestDelegate call = () => new MapTheme(invalidAttributeName, new[]
+            TestDelegate call = () => new MapTheme<TestCategoryTheme>(invalidAttributeName, new[]
             {
-                CategoryThemeTestFactory.CreateCategoryTheme()
+                CreateCategoryTheme()
             });
 
             // Assert
@@ -53,7 +52,7 @@
         public void Constructor_CategoryThemesNull_ThrowsArgumentNullException()
         {
             // Call
-            TestDelegate call = () => new MapTheme("Arbitrary attribute", null);
+            TestDelegate call = () => new MapTheme<TestCategoryTheme>("Arbitrary attribute", null);
 
             // Assert
             var exception = Assert.Throws<ArgumentNullException>(call);
@@ -63,11 +62,9 @@
         [Test]
         public void Constructor_CategoryThemesEmpty_ThrowsArgumentException()
         {
-            // Setup
-            IEnumerable<CategoryTheme> mapCategories = Enumerable.Empty<CategoryTheme>();
-
             // Call
-            TestDelegate call = () => new MapTheme("Arbitrary attribute", mapCategories);
+            TestDelegate call = () => new MapTheme<CategoryTheme>("Arbitrary attribute",
+                                                                  Enumerable.Empty<CategoryTheme>());
 
             // Assert
             const string expectedMessage = "categoryThemes is empty.";
@@ -79,17 +76,27 @@
         {
             // Setup
             const string attributeName = "Arbitrary attribute";
-            CategoryTheme[] mapCategories =
+            TestCategoryTheme[] mapCategories =
             {
-                CategoryThemeTestFactory.CreateCategoryTheme()
+                CreateCategoryTheme()
             };
 
             // Call
-            var theme = new MapTheme(attributeName, mapCategories);
+            var theme = new MapTheme<TestCategoryTheme>(attributeName, mapCategories);
 
             // Assert
             Assert.AreEqual(attributeName, theme.AttributeName);
             Assert.AreSame(mapCategories, theme.CategoryThemes);
         }
+
+        private static TestCategoryTheme CreateCategoryTheme()
+        {
+            return new TestCategoryTheme(ValueCriterionTestFactory.CreateValueCriterion());
+        }
+
+        private class TestCategoryTheme : CategoryTheme
+        {
+            public TestCategoryTheme(ValueCriterion criterion) : base(criterion) {}
+        }
     }
 }
\ No newline at end of file