anchor.diff:  -spec delete_by_name(file_meta:uuid(), xattr:name()) ->
       ok | datastore:generic_error().
   delete_by_name(FileUuid, XattrName) ->
  -    xattr:delete({FileUuid, XattrName}).
  +    xattr:delete(encode_key(FileUuid, XattrName)).
   
   %%--------------------------------------------------------------------
   %% @doc Checks existence of extended attribute with given name
   %%--------------------------------------------------------------------
   -spec exists_by_name(file_meta:uuid(), xattr:name()) -> datastore:exists_return().
   exists_by_name(FileUuid, XattrName) ->
  -    xattr:exists({FileUuid, XattrName}).
  +    xattr:exists(encode_key(FileUuid, XattrName)).
   
   %%--------------------------------------------------------------------
   %% @doc Saves extended attribute
   %%--------------------------------------------------------------------
   -spec save(file_meta:uuid(), #xattr{}) ->
       {ok, datastore:key()} | datastore:generic_error().
  -save(FileUuid, Xattr = #xattr{name = XattrKey}) ->
  -    save(#document{key = {FileUuid, XattrKey}, value = Xattr}).
  +save(FileUuid, Xattr = #xattr{name = XattrName}) ->
  +    save(#document{key = encode_key(FileUuid, XattrName), value = Xattr}).
   
   %%--------------------------------------------------------------------
   %% @doc Lists names of all extended attributes associated with given file
  
positive.code: 
  -export_type([name/0, value/0]).
  
  %%%===================================================================
  %%% API
  %%%===================================================================
  
negative.code: %%--------------------------------------------------------------------
  -spec save(datastore:document()) ->
      {ok, datastore:key()} | datastore:generic_error().
  save(Document) ->
      case datastore:save(?STORE_LEVEL, Document) of
      {ok, Key}->
          {Uuid, Name} = decode_key(Key),
          ok = datastore:add_links(?LINK_STORE_LEVEL, Uuid, ?MODEL_NAME, {?XATTR_LINK_NAME(Name), {Key, ?MODEL_NAME}}),
              {ok, Key};
          Error ->
              Error
  