Index: src/work/alpar/emptygraph.h
===================================================================
--- src/work/alpar/emptygraph.h	(revision 163)
+++ src/work/alpar/emptygraph.h	(revision 165)
@@ -19,5 +19,9 @@
   /// It can be used for checking the interface compatibility,
   /// or it can serve as a skeleton of a new graph structure.
-
+  /// 
+  /// Also, you will find here the full documentation of a certain graph
+  /// feature, the documentation of a real graph imlementation
+  /// like @ref ListGraph or
+  /// @ref SmartGraph will just refer to this structure.
   class EmptyGraph
   {
Index: src/work/alpar/invalid.h
===================================================================
--- src/work/alpar/invalid.h	(revision 162)
+++ src/work/alpar/invalid.h	(revision 165)
@@ -17,5 +17,5 @@
   /// in such a way that the value of the target iterator will be invalid.
   
-  ///extern Invalid INVALID;
+  //extern Invalid INVALID;
 
   const Invalid &INVALID = *(Invalid *)0;