diff -r ee62b0d90933 -r 08735c8704cd src/work/alpar/invalid.h
--- a/src/work/alpar/invalid.h	Sat Mar 13 22:48:43 2004 +0000
+++ b/src/work/alpar/invalid.h	Sat Mar 13 22:49:54 2004 +0000
@@ -15,7 +15,10 @@
   
   /// \ref Invalid is a global type that converts to each iterator
   /// in such a way that the value of the target iterator will be invalid.
-  
+
+  // It is also used to convert the \c INVALID constant to the
+  // node iterator that makes is possible to write 
+
   //extern Invalid INVALID;
 
   //const Invalid &INVALID = *(Invalid *)0;