diff --git a/sources/zweic/Tree.scala b/sources/zweic/Tree.scala
index b6a6b52..90e1d92 100755
--- a/sources/zweic/Tree.scala
+++ b/sources/zweic/Tree.scala
@@ -30,75 +30,49 @@
 //############################################################################
 // Tree node representing a complete program
 
-/**
- * P = Program { D } E
- */
+/* P = Program { D } E */
 case class Program(classes: List[ClassDef], main: Expr)
      extends Tree;
 
 //############################################################################
 // Tree nodes for definitions
 
-/**
- * A common superclass for all definitions
- */
+/* A common superclass for all definitions */
 abstract class Def extends Tree;
 
-/**
- * D = ClassDef name [ name ] { M }
- */
-case class ClassDef(
-// ... � compl�ter ...
-                   )
+/* D = ClassDef name [ name ] { M } */
+case class ClassDef(name: Name, extend: Option[Name], members: List [Member])
      extends Def;
 
-
-/**
- * A common superclass for member definitions
- */
+/* A common superclass for member definitions */
 abstract class Member extends Def;
 
-/**
- * M = FieldDecl name T
- */
-case class FieldDecl(
-// ... � compl�ter ...
-                    )
-     extends Member;
+/* M = FieldDecl name T */
+case class FieldDecl(name: Name, typ: TypeTree) extends Member;
 
-
-/**
- * D = MethodDecl name { name T } T E
- */
-case class MethodDef(
-// ... � compl�ter ...
-                    )
-     extends Member
-{
+/* D = MethodDecl name { F } T E */
+case class MethodDef(name: Name, args: List[Formal],
+		     returntype: TypeTree, expression: Expr)
+     extends Member {
   val self: Name = Name("this");
 }
 
+/* F = Formal name T */
+case class Formal(name: Name, typ: TypeTree) extends Tree;
+
 //############################################################################
 // Tree nodes for types
 
-/**
- * A common superclass for tree nodes designating types
- */
+/* A common superclass for tree nodes designating types */
 abstract class TypeTree extends Tree;
 
-/**
- * T = Int
- */
+/* T = Int */
 case class IntType extends TypeTree;
 
-/**
- * T = Null
- */
+/* T = Null /
 case class NullType extends TypeTree;
 
-/**
- * T = ClassType name
- */
+/* T = ClassType name */
 case class ClassType(name: Name) extends TypeTree;
 
 //############################################################################
@@ -155,6 +129,5 @@
  */
 case class Unop(op: Operator, expr: Expr) extends Expr;
 
-// ... � compl�ter ...
 
 //############################################################################