anchor.diff:  
   -include("op_logic.hrl").
   -include("modules/datastore/transfer.hrl").
  --include("modules/fslogic/fslogic_common.hrl").
   -include("http/rest/rest_api/rest_errors.hrl").
  --include_lib("ctool/include/api_errors.hrl").
   -include_lib("ctool/include/posix/errors.hrl").
   
   -export([op_logic_plugin/0]).
  --export([operation_supported/3]).
  +-export([
  +    operation_supported/3,
  +    data_spec/1,
  +    fetch_entity/1,
  +    exists/2,
  +    authorize/2,
  +    validate/2
  +]).
   -export([create/1, get/2, update/1, delete/1]).
  --export([authorize/2, data_signature/1]).
   
   -define(MAX_LIST_LIMIT, 1000).
   -define(DEFAULT_INDEX_LIST_LIMIT, 100).
  
positive.code:     end;
  
  get(#op_req{gri = #gri{id = SpaceId, aspect = {query_index, IndexName}}} = Req, _) ->
      op_logic_utils:ensure_space_supported_locally(SpaceId),
  
      Options = index_utils:sanitize_query_options(Req#op_req.data),
      case index:query(SpaceId, IndexName, Options) of
          {ok, {Rows}} ->
  
negative.code:     {ok, EffSpaces};
  
  get(#op_req{client = Cl, gri = #gri{id = SpaceId, aspect = instance}}, _) ->
      case space_logic:get(Cl#client.id, SpaceId) of
          {ok, #document{value = #od_space{name = Name, providers = ProvidersIds}}} ->
              Providers = lists:map(fun(ProviderId) ->
                  {ok, ProviderName} = provider_logic:get_name(ProviderId),
  