anchor.diff:      update_tagcontent(TagName, Field, Value, {ok, New}, Token).
   
   -spec update_tagcontent(attrib(), _, tagcontent()) ->
  -                       {'error', 'too_many_attributes' | 'invalid_url_object'} |
  -                       {'ok', tagcontent()}.
  +                       {error, too_many_attributes | invalid_url_object} |
  +                       {ok, tagcontent()}.
   update_tagcontent(read_token, Token, Tag) ->
       {ok, Tag#tagcontent{read_token = Token}};
   
  
positive.code:                    last_modified = ddfs_util:format_timestamp()}.
  
  -spec update_tagcontent(tagname(), attrib(), _, _, token()) ->
                          {'error', 'too_many_attributes' | 'invalid_url_object'} |
                          {'ok', tagcontent()}.
  update_tagcontent(TagName, Field, Value, {ok, Tag}, _Token) ->
      Updated = update_tagcontent(TagName, Tag),
      update_tagcontent(Field, Value, Updated);
  
negative.code: 
  -export([make_tagcontent/6]).
  
  -spec check_token(tokentype(), token(), token(), token()) -> tokentype() | false.
  check_token(TokenType, Token, ReadToken, WriteToken) ->
      Auth = fun(Tok, CurrentToken) when Tok =:= CurrentToken -> true;
                (internal, _) -> true;
  