diff --git a/library/s1ap/S1AP_Types.ttcn b/library/s1ap/S1AP_Types.ttcn
new file mode 100644
index 0000000..6730ff3
--- /dev/null
+++ b/library/s1ap/S1AP_Types.ttcn
@@ -0,0 +1,7 @@
+module S1AP_Types {
+
+	import from S1AP_PDU_Descriptions language "ASN.1:1997" all;
+
+	external function enc_S1AP_PDU(in S1AP_PDU pdu) return octetstring;
+	external function dec_S1AP_PDU(in octetstring stream) return S1AP_PDU;
+}