A crocodile is a Train Protection device used in France, Belgium and Luxemburg.<br/>It is usually part of a TP system such as DAAT (Dispositif d'Arret Automatique des Trains) or DAAT-A (DAAT-Avancé).<br/>Train selection properties can apply to crocodiles. For instance: crocodile équipé de reconnaissance de train de banlieue.  On top of the standard DC signal the crocodile sends a AC signal that stops Paris suburban trains selectively. <br/>