diff --git a/py_gen/templates/init.py b/py_gen/templates/init.py
index abc8d70..4a14228 100644
--- a/py_gen/templates/init.py
+++ b/py_gen/templates/init.py
@@ -30,6 +30,9 @@
 :: include('_autogen.py')
 
 import action, common, const, message
+:: if version >= 4:
+import oxm
+:: #endif
 from const import *
 from common import *
 from loxi import ProtocolError
diff --git a/py_gen/templates/oxm.py b/py_gen/templates/oxm.py
new file mode 100644
index 0000000..c210874
--- /dev/null
+++ b/py_gen/templates/oxm.py
@@ -0,0 +1,93 @@
+:: # Copyright 2013, Big Switch Networks, Inc.
+:: #
+:: # LoxiGen is licensed under the Eclipse Public License, version 1.0 (EPL), with
+:: # the following special exception:
+:: #
+:: # LOXI Exception
+:: #
+:: # As a special exception to the terms of the EPL, you may distribute libraries
+:: # generated by LoxiGen (LoxiGen Libraries) under the terms of your choice, provided
+:: # that copyright and licensing notices generated by LoxiGen are not altered or removed
+:: # from the LoxiGen Libraries and the notice provided below is (i) included in
+:: # the LoxiGen Libraries, if distributed in source code form and (ii) included in any
+:: # documentation for the LoxiGen Libraries, if distributed in binary form.
+:: #
+:: # Notice: "Copyright 2013, Big Switch Networks, Inc. This library was generated by the LoxiGen Compiler."
+:: #
+:: # You may not use this file except in compliance with the EPL or LOXI Exception. You may obtain
+:: # a copy of the EPL at:
+:: #
+:: # http://www.eclipse.org/legal/epl-v10.html
+:: #
+:: # Unless required by applicable law or agreed to in writing, software
+:: # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+:: # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+:: # EPL for the specific language governing permissions and limitations
+:: # under the EPL.
+::
+:: import itertools
+:: import of_g
+:: include('_copyright.py')
+
+:: include('_autogen.py')
+
+import struct
+import const
+import util
+import loxi
+
+class OXM(object):
+    type_len = None # override in subclass
+    pass
+
+:: for ofclass in ofclasses:
+:: nonskip_members = [m for m in ofclass.members if not m.skip]
+class ${ofclass.pyname}(OXM):
+:: for m in ofclass.type_members:
+    ${m.name} = ${m.value}
+:: #endfor
+
+    def __init__(self, ${', '.join(["%s=None" % m.name for m in nonskip_members])}):
+:: for m in nonskip_members:
+        if ${m.name} != None:
+            self.${m.name} = ${m.name}
+        else:
+            self.${m.name} = ${m.oftype.gen_init_expr()}
+:: #endfor
+
+    def pack(self):
+        packed = []
+:: include("_pack.py", ofclass=ofclass)
+        return ''.join(packed)
+
+    @staticmethod
+    def unpack(buf):
+        obj = ${ofclass.pyname}()
+:: include("_unpack.py", ofclass=ofclass)
+        return obj
+
+    def __eq__(self, other):
+        if type(self) != type(other): return False
+:: for m in nonskip_members:
+        if self.${m.name} != other.${m.name}: return False
+:: #endfor
+        return True
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def show(self):
+        import loxi.pp
+        return loxi.pp.pp(self)
+
+    def pretty_print(self, q):
+:: include('_pretty_print.py', ofclass=ofclass)
+
+:: #endfor
+
+parsers = {
+:: key = lambda x: int(x.type_members[0].value, 16)
+:: for ofclass in sorted(ofclasses, key=key):
+    ${key(ofclass)} : ${ofclass.pyname}.unpack,
+:: #endfor
+}