diff --git a/ui/cli.py b/ui/cli.py
index b759262..d7bb71a 100644
--- a/ui/cli.py
+++ b/ui/cli.py
@@ -66,18 +66,30 @@ class MDBase(object):
 		If the correct type is not found, a ValueError is raised.'''
 
 		if isinstance(obj, cls):
-			# XXX - copy?
-			return obj
+			obj = obj._obj
 
 		ty = obj['type']
 
-		for i in cls.__subclasses__():
+		for i in MDBase.__subclasses__():
 			if i._type == ty:
 				return i(obj)
 		else:
 			raise ValueError('Unable to find class for type %s' %
 			    `ty`)
 
+	def new_version(self, *args):
+		'''Add the property k as an additional one (or new on if
+		first), with the value v.'''
+
+		obj = copy.deepcopy(self._obj)
+
+		for k, v in args:
+			obj.setdefault(k, []).append(v)
+
+		del obj['modified']
+
+		return self.create_obj(obj)
+
 	def __getattr__(self, k):
 		return self._obj[k]
 
@@ -90,6 +102,9 @@ class MDBase(object):
 	def __eq__(self, o):
 		return cmp(self._obj, o) == 0
 
+	def __contains__(self, k):
+		return k in self._obj
+
 	def items(self, skipcommon=True):
 		return [ (k, v) for k, v in self._obj.items() if k not in
 		    self._common_names ]
@@ -317,10 +332,32 @@ class _TestCases(unittest.TestCase):
 			'created_by_ref': self.created_by_ref,
 		}
 		origbase = copy.deepcopy(baseobj)
+
+		# that when an MDBase object is created
 		md = MDBase.create_obj(baseobj)
 
+		# it doesn't modify the passed in object (when adding
+		# generated properties)
 		self.assertEqual(baseobj, origbase)
 
+		# and it has the generted properties
+		# Note: cannot mock the functions as they are already
+		# referenced at creation time
+		self.assertIn('uuid', md)
+		self.assertIn('modified', md)
+
+		# That you can create a new version using new_version
+		md2 = md.new_version(('dc:creator', 'Jim Bob',))
+
+		# that they are different
+		self.assertNotEqual(md, md2)
+
+		# and that the new modified time is different from the old
+		self.assertNotEqual(md.modified, md2.modified)
+
+		# and that the modification is present
+		self.assertEqual(md2['dc:creator'], [ 'Jim Bob' ])
+
 	def test_makehash(self):
 		self.assertRaises(ValueError, ObjectStore.makehash, 'slkj')
 		self.assertRaises(ValueError, ObjectStore.makehash, 'sha256:91751cee0a1ab8414400238a761411daa29643ab4b8243e9a91649e25be53ADA')
@@ -376,7 +413,7 @@ class _TestCases(unittest.TestCase):
 		r = byid
 
 		self.assertEqual(r.uuid, '3e466e06-45de-4ecc-84ba-2d2a3d970e96')
-		self.assertEqual(r['dc:creator'], 'John-Mark Gurney')
+		self.assertEqual(r['dc:creator'], [ u'John-Mark Gurney' ])
 
 		fname = 'testfile.pasn1'
 		objst.store(fname)
diff --git a/ui/fixtures/genfixtures.py b/ui/fixtures/genfixtures.py
index 568a22d..fba0fec 100644
--- a/ui/fixtures/genfixtures.py
+++ b/ui/fixtures/genfixtures.py
@@ -11,7 +11,7 @@ map(objst.loadobj,
 			'uuid': '3e466e06-45de-4ecc-84ba-2d2a3d970e96',
 			'created_by_ref': cbr,
 			'modified': datetime.datetime(2019, 5, 31, 14, 5, 3),
-			'dc:creator': u'John-Mark Gurney',
+			'dc:creator': [ u'John-Mark Gurney' ],
 			'hashes': [ 'sha256:91751cee0a1ab8414400238a761411daa29643ab4b8243e9a91649e25be53ada', 'sha512:7d5768d47b6bc27dc4fa7e9732cfa2de506ca262a2749cb108923e5dddffde842bbfee6cb8d692fb43aca0f12946c521cce2633887914ca1f96898478d10ad3f' ],
 			'lang': 'en'
 		}