diff --git a/sources/zweic/Tree.scala b/sources/zweic/Tree.scala
index 2d5663e..b6a6b52 100755
--- a/sources/zweic/Tree.scala
+++ b/sources/zweic/Tree.scala
@@ -19,7 +19,7 @@
 
   /**
    * The source code position of this tree node.
-   * Has to be set explicitly woth the setPos method
+   * Has to be set explicitly with the setPos method
    */
   private var p: Int = Position.UNDEFINED;
   def pos: Int = p;
@@ -42,15 +42,16 @@
 /**
  * A common superclass for all definitions
  */
-abstract class Def extends Tree {
-  def name: Name;
-}
+abstract class Def extends Tree;
 
 /**
  * D = ClassDef name [ name ] { M }
  */
-abstract case class ClassDef( ) extends Def {};
-//TODO
+case class ClassDef(
+// ... � compl�ter ...
+                   )
+     extends Def;
+
 
 /**
  * A common superclass for member definitions
@@ -60,17 +61,22 @@
 /**
  * M = FieldDecl name T
  */
-abstract case class FieldDecl( ) extends Member;
-//TODO
+case class FieldDecl(
+// ... � compl�ter ...
+                    )
+     extends Member;
+
 
 /**
  * D = MethodDecl name { name T } T E
  */
-abstract case class MethodDef( ) extends Member
+case class MethodDef(
+// ... � compl�ter ...
+                    )
+     extends Member
 {
   val self: Name = Name("this");
 }
-//TODO
 
 //############################################################################
 // Tree nodes for types