diff --git a/src/helma/framework/core/Application.java b/src/helma/framework/core/Application.java
index 280fa9d6..79cc699e 100644
--- a/src/helma/framework/core/Application.java
+++ b/src/helma/framework/core/Application.java
@@ -984,6 +984,23 @@ public final class Application implements Runnable {
         return typemgr.getPrototypes();
     }
 
+    /**
+     * Programmatically define a new prototype. If a prototype with this name already exists return
+     * the existing prototype.
+     * @param name the prototype name
+     * @param typeProps custom type properties map
+     * @return the new prototype
+     */
+    public Prototype definePrototype(String name, Map typeProps) {
+        Prototype proto = typemgr.getPrototype(name);
+        if (proto == null) {
+            proto = typemgr.createPrototype(name, null, typeProps);
+        } else {
+            proto.setTypeProperties(typeProps);
+        }
+        return proto;
+    }
+
     /**
      *  Return a skin for a given object. The skin is found by determining the prototype
      *  to use for the object, then looking up the skin for the prototype.
diff --git a/src/helma/framework/core/Prototype.java b/src/helma/framework/core/Prototype.java
index 126db96b..17d5994c 100644
--- a/src/helma/framework/core/Prototype.java
+++ b/src/helma/framework/core/Prototype.java
@@ -74,8 +74,9 @@ public final class Prototype {
      * @param name the prototype's name
      * @param repository the first prototype's repository
      * @param app the application this prototype is a part of
+     * @param typeProps custom type mapping properties
      */
-    public Prototype(String name, Repository repository, Application app) {
+    public Prototype(String name, Repository repository, Application app, Map typeProps) {
         // app.logEvent ("Constructing Prototype "+app.getName()+"/"+name);
         this.app = app;
         this.name = name;
@@ -87,10 +88,13 @@ public final class Prototype {
 
         // Create and register type properties file
         props = new ResourceProperties(app);
-        if (repository != null) {
+        if (typeProps != null) {
+            props.putAll(typeProps);
+        } else if (repository != null) {
             props.addResource(repository.getResource("type.properties"));
             props.addResource(repository.getResource(name + ".properties"));
         }
+
         dbmap = new DbMapping(app, name, props);
         // we don't need to put the DbMapping into proto.updatables, because
         // dbmappings are checked separately in TypeManager.checkFiles() for
@@ -392,6 +396,16 @@ public final class Prototype {
         lastCodeUpdate = System.currentTimeMillis();
     }
 
+    /**
+     * Set the custom type properties for this prototype and update the database mapping.
+     * @param map the custom type mapping properties.
+     */
+    public void setTypeProperties(Map map) {
+        props.clear();
+        props.putAll(map);
+        dbmap.update();
+    }
+
     /**
      * Get the prototype's aggregated type.properties
      *
diff --git a/src/helma/framework/core/TypeManager.java b/src/helma/framework/core/TypeManager.java
index d6696c28..b982ac09 100644
--- a/src/helma/framework/core/TypeManager.java
+++ b/src/helma/framework/core/TypeManager.java
@@ -104,7 +104,7 @@ public final class TypeManager {
     public synchronized void createPrototypes() throws IOException {
         // create standard prototypes.
         for (int i = 0; i < standardTypes.length; i++) {
-            createPrototype(standardTypes[i], null);
+            createPrototype(standardTypes[i], null, null);
         }
 
         // loop through directories and create prototypes
@@ -154,7 +154,7 @@ public final class TypeManager {
                 if (proto == null) {
                     // create new prototype if type name is valid
                     if (isValidTypeName(name)) 
-                        createPrototype(name, list[i]);
+                        createPrototype(name, list[i], null);
                 } else {
                     proto.addRepository(list[i], update);
                 }
@@ -294,14 +294,15 @@ public final class TypeManager {
      *
      * @param typename the name of the prototype
      * @param repository the first prototype source
+     * @param typeProps custom type mapping properties
      * @return the newly created prototype
      */
-    public synchronized Prototype createPrototype(String typename, Repository repository) {
+    public synchronized Prototype createPrototype(String typename, Repository repository, Map typeProps) {
         if ("true".equalsIgnoreCase(app.getProperty("helma.debugTypeManager"))) {
             System.err.println("CREATE: " + typename + " from " + repository + " in " + Thread.currentThread());
             // Thread.dumpStack();
         }
-        Prototype proto = new Prototype(typename, repository, app);
+        Prototype proto = new Prototype(typename, repository, app, typeProps);
         // put the prototype into our map
         prototypes.put(proto.getLowerCaseName(), proto);
         return proto;
diff --git a/src/helma/scripting/rhino/GlobalObject.java b/src/helma/scripting/rhino/GlobalObject.java
index c39e77a4..341c0a1e 100644
--- a/src/helma/scripting/rhino/GlobalObject.java
+++ b/src/helma/scripting/rhino/GlobalObject.java
@@ -73,7 +73,7 @@ public class GlobalObject extends ImporterTopLevel implements PropertyRecorder {
                                    "getXmlDocument", "getHtmlDocument", "seal",
                                    "getDBConnection", "getURL", "write", "writeln",
                                    "serialize", "deserialize", "defineLibraryScope",
-                                   "wrapJavaMap", "unwrapJavaMap", "toJava"
+                                   "wrapJavaMap", "unwrapJavaMap", "toJava", "definePrototype"
                                };
 
         defineFunctionProperties(globalFuncs, GlobalObject.class, DONTENUM | PERMANENT);
@@ -673,6 +673,24 @@ public class GlobalObject extends ImporterTopLevel implements PropertyRecorder {
         return null;
     }
 
+    public Object definePrototype(String name, Scriptable desc) {
+        if (name == null) {
+            throw new IllegalArgumentException("First argument to definePrototype() must be String");
+        }
+        if (desc == null) {
+            throw new IllegalArgumentException("Second argument to definePrototype() must be Object");
+        }
+
+        Prototype proto = core.app.definePrototype(name, core.scriptableToProperties(desc));
+        RhinoCore.TypeInfo type = (RhinoCore.TypeInfo) core.prototypes.get(proto.getLowerCaseName());
+        if (type == null) {
+            type = core.initPrototype(proto);
+        }
+        core.setParentPrototype(proto, type);
+        return type.objProto;
+    }
+
+
     private static String toString(Object obj) {
         if (obj == null || obj == Undefined.instance) {
             // Note: we might return "" here in order