plain non-dependent types;

--- a/src/Pure/Isar/isar_document.scala	Tue Jan 27 15:22:46 2009 +0100
+++ b/src/Pure/Isar/isar_document.scala	Tue Jan 27 15:47:22 2009 +0100
@@ -6,14 +6,17 @@
 
 package isabelle
 
-
-trait IsarDocument extends IsabelleProcess
-{
+object IsarDocument {
   /* unique identifiers */
 
   type State_ID = String
   type Command_ID = String
   type Document_ID = String
+}
+
+trait IsarDocument extends IsabelleProcess
+{
+  import IsarDocument._
 
 
   /* commands */