Ошибка BASEDIR на php7.3 - Как исправить?

Старый код не работает на php7.3 получаю предупреждение:

Warning: Use of undefined constant BASEDIR - assumed 'BASEDIR' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\sitecopy\includes\bbcodes\url_bbcode_include.php on line 27

Warning: Use of undefined constant BASEDIR - assumed 'BASEDIR' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\sitecopy\includes\bbcodes\url_bbcode_include.php on line 27

Warning: Use of undefined constant INCLUDES - assumed 'INCLUDES' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\sitecopy\includes\bbcodes\url_bbcode_include.php on line 29

Подскажите пожалуйста как исправить? Не силён я в кодировании. Вот две строчки старого кода:

$guest_msg = '[ ссылка скрыта ] ( <a href="'.BASEDIR.'register.php"><u>регистрация</u></a> | <a href="'.BASEDIR.'login.php"><u>вход</u></a> )';

$pathto = ($friendlyurl?BASEDIR.$friendlypath.'?':INCLUDES.'bbcodes/url_bbcode_include.php?');