--- a/UndefinedObject.st	Thu Jun 02 13:36:22 1994 +0200
+++ b/UndefinedObject.st	Thu Jun 02 18:22:49 1994 +0200
@@ -18,14 +18,46 @@
 !
 
 UndefinedObject comment:'
+COPYRIGHT (c) 1988 by Claus Gittinger
+              All Rights Reserved
+'!
 
-COPYRIGHT (c) 1988 by Claus Gittinger
+!UndefinedObject class methodsFor:'documentation'!
+
+copyright
+"
+ COPYRIGHT (c) 1988 by Claus Gittinger
               All Rights Reserved
 
-there is only one instance of this class: nil
+ This software is furnished under a license and may be used
+ only in accordance with the terms of that license and with the
+ inclusion of the above copyright notice.   This software may not
+ be provided or otherwise made available to, or used by, any
+ other person.  No title to or ownership of the software is
+ hereby transferred.
+"
+!
+
+version
+"
+$Header: /cvs/stx/stx/libbasic/UndefinedObject.st,v 1.10 1994-06-02 16:22:37 claus Exp $
+"
+!
 
-$Header: /cvs/stx/stx/libbasic/UndefinedObject.st,v 1.9 1994-05-17 10:09:34 claus Exp $
-'!
+documentation
+"
+    there is only one instance of this class: nil, representing an undefined
+    or otherwise unspecified object.
+
+    All instance variables, array elements and even method/block local 
+    variables are initially set to nil.
+    Since in Smalltalk/X, nil is represented by a special pointer value,
+    there can be only one instance of UndefinedObject, and no subclassing is
+    possible. 
+    (to be exact: subclassing is technically possible, but instances of it 
+     would not be recognized as being nil - therefore, subclassing is blocked)
+"
+! !
 
 !UndefinedObject class methodsFor:'instance creation'!