diff --git a/doc/user/datatypes.t b/doc/user/datatypes.t
index 4dcf2adc4a..720bfb0e57 100644
--- a/doc/user/datatypes.t
+++ b/doc/user/datatypes.t
@@ -1,4 +1,4 @@
-c
+@c
 @c  COPYRIGHT (c) 1988-2000.
 @c  On-Line Applications Research Corporation (OAR).
 @c  All rights reserved.