diff --git a/library/TRXC_Types.ttcn b/library/TRXC_Types.ttcn
index 77666d9..37b8610 100644
--- a/library/TRXC_Types.ttcn
+++ b/library/TRXC_Types.ttcn
@@ -1,5 +1,15 @@
 module TRXC_Types {
 
+/* TRX Control protocol type definitions in TTCN-3
+ * (C) 2018 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.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
 import from Osmocom_Types all;
 
 type charstring TrxcType ("CMD", "RSP", "IND") with {