What is the lock called which is built in to the back of a peugeot vivacity 50 50cc moped?

in the back of my moped i put the key in and pull out a long thick chain to tie the bike up. on the insurance quote there is a whole list of lock names, what is the name of the chain on the peugeot vivacity?|||on my peugeot scooter it has a trelock chain