diff --git a/Common/derived_types.f90 b/Common/derived_types.f90
index 992a83a149cb5015bf05723b31f8bb8c14a693bb..2d92f36200cef617092c67de4e125dfb0c5f8645 100644
--- a/Common/derived_types.f90
+++ b/Common/derived_types.f90
@@ -43,11 +43,12 @@ module derived_types
   end type eddy
 
   type snapshot
-     type(eddy), allocatable:: list(:) ! (number_extr)
-     ! Visible "eddies" at a given date. These include "eddies"
-     ! without an outermost contour, that is only the extremum is
-     ! visible. The subscript value in list is the "identification
-     ! number" of the extremum.
+     type(eddy), allocatable:: list(:) ! (number_extr) Visible
+     ! "eddies" at a given date. In general, they can have both
+     ! orientations. Visible eddies include "eddies" without an
+     ! outermost contour, that is only the extremum is visible. The
+     ! subscript value in list is the "identification number" of the
+     ! extremum.
      
      integer number_extr ! number of visible extrema