anchor.diff:              end
           end);
   update(#model_config{bucket = _Bucket, name = ModelName} = ModelConfig, Key, Diff) when is_map(Diff) ->
  -    datastore:run_transaction(ModelName, synchronization_link_key(ModelConfig, Key),
  +    datastore:run_transaction(ModelName, synchronization_doc_key(ModelConfig, Key),
           fun() ->
               case get(ModelConfig, Key) of
                   {error, Reason} ->
  
positive.code: %%--------------------------------------------------------------------
  -spec force_save(model_behaviour:model_config(), binary(), datastore:document()) ->
      {ok, datastore:ext_key()} | datastore:generic_error().
  force_save(#model_config{name = ModelName} = ModelConfig, BucketOverride, #document{key = Key, rev = {RNum, [Id | _]}} = ToSave) ->
      datastore:run_transaction(ModelName, synchronization_link_key(ModelConfig, Key),
          fun() ->
              case get(ModelConfig, Key) of
                  {error, {not_found, _}} ->
  
negative.code:         end);
  create_or_update(#model_config{name = ModelName} = ModelConfig, #document{key = Key} = NewDoc, Diff)
      when is_map(Diff) ->
      datastore:run_transaction(ModelName, synchronization_doc_key(ModelConfig, Key),
          fun() ->
              case get(ModelConfig, Key) of
                  {error, {not_found, ModelName}} ->
  