Copyright for 1992 added
diff --git a/Include/opcode.h b/Include/opcode.h
index 43b8d3e..a0db342 100644
--- a/Include/opcode.h
+++ b/Include/opcode.h
@@ -1,5 +1,5 @@
 /***********************************************************
-Copyright 1991 by Stichting Mathematisch Centrum, Amsterdam, The
+Copyright 1991, 1992 by Stichting Mathematisch Centrum, Amsterdam, The
 Netherlands.
 
                         All Rights Reserved