--- a/Character.st	Tue Jun 20 15:38:43 2017 +0200
+++ b/Character.st	Tue Jun 20 17:21:51 2017 +0200
@@ -319,14 +319,26 @@
     "Answer the Character representing ctrl-char.
      ctrl-a -> 1; ctrl-@ -> 0"
 
-    char == $@ ifTrue:[^ self codePoint:0].
-    self assert:char isLetter.
-    ^ self codePoint:(char asLowercase - $a + 1)
+    |lcChar|
+
+    char == $@ ifTrue:[^ Character value:0 ].
+    
+    lcChar := char asUppercase.
+    self assert:(lcChar between:$A and:$Z+5).
+    ^ self codePoint:(lcChar - $A + 1)
 
     "
-     self controlCharacter:$@
-     self controlCharacter:$d
+     self controlCharacter:$@ -> 0
+     self controlCharacter:$a -> 1
+     self controlCharacter:$d -> 4
+     self controlCharacter:$z -> 26
+     self controlCharacter:$[ -> 27    
+     self controlCharacter:$\ -> 28     
+     self controlCharacter:$] -> 29
+     self controlCharacter:$_ -> 31     
     "
+
+    "Modified (comment): / 20-06-2017 / 17:20:21 / cg"
 !
 
 endOfInput
@@ -601,7 +613,6 @@
     "
 ! !
 
-
 !Character methodsFor:'Compatibility-Dolphin'!
 
 isAlphaNumeric
@@ -650,7 +661,6 @@
 ! !
 
 
-
 !Character methodsFor:'accessing'!
 
 codePoint