The strippenkaart, introduced on 1 October 1980 and abolished on 3 November 2011, was a ticket composed of several strips, to be validated when used. Passengers either validated the ticket themselves in a machine, or got it stamped by the driver or conductor. The number of strips to be cancelled was always the number of zones travelled plus one, up to a maximum of 20 strips. The stamped ticket was valid for an hour for two to four strips, up to three and a half hours for 17 to 20 strips.