anchor.diff:  				 [ << MixinScheme/binary, MixinTerm/binary >> | Acc ]
   			 end, [], occi_entity:mixins(Entity)),
   	     occi_entity:raw_attributes(Entity),
  -	     Owner,
  -	     Group
  +	     marshal_user(Owner),
  +	     marshal_user(Group)
   	   ],
       case dbus_proxy:call(Backend, ?IFACE_BACKEND, <<"Create1">>, Args) of
   	{ok, [KindId, MixinIds, Attributes, Serial]} ->
   	    Entity2 = unmarshal_entity(KindId, MixinIds, Attributes),
   	    {{ok, Entity2, unmarshal_serial(Serial)}, S};
  -	{error, _}=Err ->
  -	    {Err, S}
  +	{error, Err} ->
  +	    dbus_errors(Err, S)
       end.
   
   
  
positive.code: 		    {ok | {error, erocci_backend:error()}, NewState :: term()}.
  delete(Location, #state{ proxy=Backend }=S) ->
      ?info("[~p] delete(~s)", [?MODULE, Location]),
      Ret = dbus_proxy:call(Backend, ?IFACE_BACKEND, [Location]),
      {Ret, S}.
  
  
  -spec mixin(Location :: occi_uri:url(), MixinId :: occi_mixin:t(), Attributes :: maps:map(), State :: term()) ->
  
negative.code: link(Location, Type, LinkId, #state{ proxy=Backend }=S) ->
      ?info("[~p] link(~s)", [?MODULE, Location]),
      Args = [ Location, ?link_types(Type), LinkId ],
      case dbus_proxy:call(Backend, ?IFACE_BACKEND, Args) of
  	ok ->
  	    {ok, S};
  	{error, Err} ->
  	    dbus_errors(Err, S)
      end.
  
  
  -spec action(Location :: occi_uri:url(), ActionId :: occi_action:id(), Attributes :: maps:map(), State :: term()) ->
  