diff --git a/library/Osmocom_CTRL_Types.ttcn b/library/Osmocom_CTRL_Types.ttcn
index 4d2406d..1d77668 100644
--- a/library/Osmocom_CTRL_Types.ttcn
+++ b/library/Osmocom_CTRL_Types.ttcn
@@ -1,5 +1,15 @@
 module Osmocom_CTRL_Types {
 
+/* Definition of abstract types for the CTRL protocol as used in Osmocom.
+ * Uses the TITAN "TEXT" codec to auto-generate encoder/decoder functions.
+ *
+ * (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.
+ */
+
 type charstring CtrlVerb ("GET", "SET") with {
 	/* see https://www.eclipse.org/forums/index.php/t/1088893/ on why this
 	 * match expression is needed here */