diff --git a/src/m2ua.hrl b/src/m2ua.hrl
new file mode 100644
index 0000000..26f10fc
--- /dev/null
+++ b/src/m2ua.hrl
@@ -0,0 +1,59 @@
+
+% RFC 3331 Section 3.1.3 Message Class
+-define(M2UA_MSGC_MGMT,		0).	% Management Messages [IUA/M2UA/M3UA/SUA]
+-define(M2UA_MSGC_TRANSFER,	1).	% Transfer Messages [M3UA]
+-define(M2UA_MSGC_SSNM,		2).	% SS7 Signalling Network Management [M3UA/SUA]
+-define(M2UA_MSGC_ASPSM,	3).	% ASP State Maintenance [IUA/M2UA/M3UA/SUA]
+-define(M2UA_MSGC_ASPTM,	4).	% ASP Traffic Maintenance [IUA/M2UA/M3UA/SUA]
+-define(M2UA_MSGC_QPTM,		5).	% Q.921/Q.931 Boundary Primitives Transport [IUA]
+-define(M2UA_MSGC_MAUP,		6).	% MTP2 User Adaption [M2UA]
+-define(M2UA_MSGC_CONNLESS,	7).	% Connectionless Messages [SUA]
+-define(M2UA_MSGC_CONN,		8).	% Connection oriented messages [SUA]
+-define(M2UA_MSGC_RKM,		9).	% Routing Key Management [M3UA]
+-define(M2UA_MSGC_IIM,		10).	% Interface Identifier Management (M2UA)
+
+% RFC 3331 Section 3.1.4 Message Type
+-define(M2UA_MAUP_MSGT_RESERVED,	0).
+-define(M2UA_MAUP_MSGT_DATA,		1).
+-define(M2UA_MAUP_MSGT_EST_REQ,		2).
+-define(M2UA_MAUP_MSGT_EST_CONF,	3).
+-define(M2UA_MAUP_MSGT_REL_REQ,		4).
+-define(M2UA_MAUP_MSGT_REL_CONF,	5).
+-define(M2UA_MAUP_MSGT_REL_IND,		6).
+-define(M2UA_MAUP_MSGT_STATE_REQ,	7).
+-define(M2UA_MAUP_MSGT_STATE_CONF,	8).
+-define(M2UA_MAUP_MSGT_STATE_IND,	9).
+-define(M2UA_MAUP_MSGT_DATA_RETR_REQ,	10).
+-define(M2UA_MAUP_MSGT_DATA_RETR_CONF,	11).
+-define(M2UA_MAUP_MSGT_DATA_RETR_IND,	12).
+-define(M2UA_MAUP_MSGT_DATA_RETR_COMPL_IND,	13).
+-define(M2UA_MAUP_MSGT_CONG_IND,	14).
+-define(M2UA_MAUP_MSGT_DATA_ACK,	15).
+
+
+-define(M2UA_ASPSM_MSGT_UP,		0).
+-define(M2UA_ASPSM_MSGT_DOWN,		1).
+-define(M2UA_ASPSM_MSGT_BEAT,		2).
+-define(M2UA_ASPSM_MSGT_UP_ACK,		3).
+-define(M2UA_ASPSM_MSGT_DOWN_ACK,	5).
+-define(M2UA_ASPSM_MSGT_BEAT_ACK,	6).
+
+-define(M2UA_ASPTM_MSGT_ACTIVE,		1).
+-define(M2UA_ASPTM_MSGT_INACTIVE,	2).
+-define(M2UA_ASPTM_MSGT_ACTIVE_ACK,	3).
+-define(M2UA_ASPTM_MSGT_INACTIVE_ACK,	4).
+
+-define(M2UA_MGMT_MSGT_ERROR,		0).
+-define(M2UA_MGMT_MSGT_NOTIFY,		1).
+
+-define(M2UA_MGMT_IIM_REG_REQ,		1).
+-define(M2UA_MGMT_IIM_REG_RSP,		2).
+-define(M2UA_MGMT_IIM_DEREG_REQ,	3).
+-define(M2UA_MGMT_IIM_DEREG_RSP,	4).
+
+-record(m2ua_msg, {
+	msg_class,
+	msg_type,
+	parameters
+	}).
+