anchor.diff:  %% @doc All view privileges in OZ API.
   %%--------------------------------------------------------------------
   -spec oz_viewer() -> [oz_privilege()].
  -oz_viewer() -> [
  -    list_users,
  -
  -    list_groups,
  -
  -    list_spaces,
  -    list_providers_of_space,
  -
  -    list_providers,
  -    list_users_of_provider,
  -    list_groups_of_provider,
  -    list_spaces_of_provider
  -].
  +oz_viewer() ->
  +    ordsets:from_list([
  +        list_users,
  +
  +        list_groups,
  +
  +        list_spaces,
  +        list_providers_of_space,
  +
  +        list_providers,
  +        list_users_of_provider,
  +        list_groups_of_provider,
  +        list_spaces_of_provider
  +    ]).
   
   
   %%--------------------------------------------------------------------
  
positive.code: %%% API
  %%%===================================================================
  
  union(PrivilegesA, PrivilegesB) ->
      ordsets:union(
          ordsets:from_list(PrivilegesA),
          ordsets:from_list(PrivilegesB)
      ).
  
  
  proplists_union(PrivilegesProplist) ->
      PrivilegesMap = lists:foldl(
          fun({Id, Privs}, AccMap) ->
              NewPrivs = case maps:get(Id, AccMap, undefined) of
                  undefined ->
                      ordsets:from_list(Privs);
                  OtherPrivs ->
                      union(Privs, OtherPrivs)
              end,
              maps:put(Id, NewPrivs, AccMap)
          end, #{}, PrivilegesProplist),
      ordsets:from_list(maps:to_list(PrivilegesMap)).
  
  
  %%--------------------------------------------------------------------
  %% @doc A privilege level of a Space user.
  %%--------------------------------------------------------------------
  -spec space_user() -> [space_privilege()].
  space_user() ->
      [space_view_data, space_write_files].
  
  %%--------------------------------------------------------------------
  %% @doc A privilege level of a Space manager.
  
negative.code: %%--------------------------------------------------------------------
  -spec handle_service_user() -> [handle_service_privilege()].
  handle_service_user() ->
      ordsets:from_list([view_handle_service, register_handle]).
  
  %%--------------------------------------------------------------------
  %% @doc A privilege level of a handle_service administrator. This level contains all
  