anchor.diff:                                           object=Object,
                                            location={Meeting, Domain},
                                            conditions=Conditions}),
  +    catch uce_event:add(#uce_event{domain=Domain,
  +                                   from={To, Domain},
  +                                   type="internal.acl.add",
  +                                   location={Meeting, Domain},
  +                                   metadata=[{"action", Action},
  +                                             {"object", Object}] ++ Conditions}),
       json_helpers:created().
   
   delete(Domain, [To, Object, Action], Params, Arg) ->
  
positive.code:     check(Domain, [To, Object, Action, ""], Params, Arg);
  check(Domain, [To, Object, Action, Meeting], [Uid, Sid, Conditions], _) ->
      {ok, true} = uce_presence:assert({Uid, Domain}, Sid),
      {ok, true} = uce_acl:assert({Uid, Domain}, "acl", "check", {Meeting, Domain},
                                  [{"user", To},
                                   {"action", Action},
                                   {"object", Object},
                                   {"meeting", Meeting}]),
      case uce_acl:check({To, Domain}, Object, Action, {Meeting, Domain}, Conditions) of
          {ok, true} ->
              json_helpers:true();
  
negative.code: add(Domain, [To, Object, Action, Meeting], [Uid, Sid, Conditions], _) ->
      {ok, true} = uce_presence:assert({Uid, Domain}, Sid),
      {ok, true} = uce_acl:assert({Uid, Domain}, "acl", "add", {Meeting, Domain},
                                  [{"action", Action},
                                   {"object", Object},
                                   {"meeting", Meeting}]),
      {ok, created} = uce_acl:add(#uce_acl{user={To, Domain},
  