found in config.php
Code:
define('INCL_DIR', dirname(__FILE__).DIRECTORY_SEPARATOR);
define('ROOT_DIR', realpath(INCL_DIR.'..'.DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR);
define('ADMIN_DIR', ROOT_DIR.'admin'.DIRECTORY_SEPARATOR);
define('FORUM_DIR', ROOT_DIR.'forums'.DIRECTORY_SEPARATOR);
define('PM_DIR', ROOT_DIR.'pm_system'.DIRECTORY_SEPARATOR);
define('CACHE_DIR', ROOT_DIR.'cache'.DIRECTORY_SEPARATOR);
pretty basic and pre defined