diff --git a/sources/zweic/Tree.scala b/sources/zweic/Tree.scala
index 123fdcf..2d5663e 100755
--- a/sources/zweic/Tree.scala
+++ b/sources/zweic/Tree.scala
@@ -49,11 +49,8 @@
 /**
  * D = ClassDef name [ name ] { M }
  */
-case class ClassDef(
-// ... � compl�ter ...
-                   )
-     extends Def;
-
+abstract case class ClassDef( ) extends Def {};
+//TODO
 
 /**
  * A common superclass for member definitions
@@ -63,19 +60,17 @@
 /**
  * M = FieldDecl name T
  */
-case class FieldDecl(
-// ... � compl�ter ...
-                    )
-     extends Member;
-
+abstract case class FieldDecl( ) extends Member;
+//TODO
 
 /**
- * D = MethodDecl name name { name T } T E
+ * D = MethodDecl name { name T } T E
  */
-case class MethodDef(
-// ... � compl�ter ...
-                    )
-     extends Member;
+abstract case class MethodDef( ) extends Member
+{
+  val self: Name = Name("this");
+}
+//TODO
 
 //############################################################################
 // Tree nodes for types