Co robi \ (ukośnik odwrotny) w PHP (5.3+)?

Co robi \w PHP? Na przykład, CSRF4PHP ma \FALSE, \session_idi \Exception: public function __construct($timeout=300, $acceptGet=\FALSE){ $this->timeout = $timeout; if (\session_id()) { $this->acceptGet = (bool) $acceptGet; } else { throw new \Exception('Could not find session id', 1);...