diff --git a/library/NAS_Templates.ttcn b/library/NAS_Templates.ttcn
index 2e8be0e..f132c4e 100644
--- a/library/NAS_Templates.ttcn
+++ b/library/NAS_Templates.ttcn
@@ -326,6 +326,15 @@
 	 activeFlag := activeFlag
 }
 
+/* 9.9.3.21 NAS key set identifier */
+const BIT3 c_NAS_KEY_SET_ID_NO_KEY := '111'B;
+const BIT1 c_NAS_TSC_NATIVE_SEC_CTX := '0'B;
+const BIT1 c_NAS_TSC_MAPPED_SEC_CTX := '1'B;
+template (value) NAS_KeySetIdentifierV ts_NAS_KeySetIdentifierV(BIT3 identifier := c_NAS_KEY_SET_ID_NO_KEY, BIT1 tSC := c_NAS_TSC_NATIVE_SEC_CTX) := {
+	 identifier := identifier,
+	 tSC := tSC
+}
+
 /* 8.2.3 Attach Reject */
 template (value) PDU_NAS_EPS
 ts_NAS_AttachReject(template (value) EMM_CauseV cause) := {