For a small fee (about €2-€5) a “Bicycode” is etched on the frame.
If the bike is stolen you record the theft at www.bicycode.org or by calling 0825 560 030 before reporting the theft to police.
If it is found the police (or anyone else) can check the site’s database so as to return it to you. Visit a participating shop (see www.bicycode.org/operateurs.php), with ownership documents such as a receipt and/or your passport or ID card.
The scheme is run by a cyclists’ association with government support.