diff --git a/library/RSL_Types.ttcn b/library/RSL_Types.ttcn
index 0604440..f42b7fd 100644
--- a/library/RSL_Types.ttcn
+++ b/library/RSL_Types.ttcn
@@ -1,5 +1,16 @@
 module RSL_Types {
 
+/* GSUP_Types, defining abstract TTCN-3 data types for the A-bis RSL protocol.
+ *
+ * RSL is a 3GPP standard protocol used between BTS and BSC in a GSM network.
+ *
+ * (C) 2017 by Harald Welte <laforge@gnumonks.org>
+ * All rights reserved.
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ */
+
 	import from General_Types all;
 	import from Osmocom_Types all;
 	import from GSM_Types all;