diff --git a/BloubWorld/povstuff.f90 b/BloubWorld/povstuff.f90
index f7dad59..c356525 100644
--- a/BloubWorld/povstuff.f90
+++ b/BloubWorld/povstuff.f90
@@ -22,6 +22,13 @@ module povstuff
 
   ! ----------------------------------------------------------------
 
+  subroutine start_of_inc_file (fd)
+    integer, intent (in)             :: fd
+
+    write(fd, '(A)') "// DON'T EDIT THIS FILE !"
+
+  end subroutine
+
   ! ----------------------------------------------------------------
   ! we need some primitives for the gestion of colors.
   ! may be a small database indexed by name ?