According to Ofcom, the watershed on standard television in the UK starts at 9:00 p.m., and finishes at 5:30 a.m. the next morning. Programmes that are 15+ are shown during this period. However, some 12+ shows can be shown before 09:00 p.m., such as The Simpsons, Malcolm in the Middle and Doctor Who. On premium film or pay-per-view services requiring a subscription, the watershed starts at 8:00 p.m. However, 12, 15 and 18 rated films can be shown on PIN protected channels (such as Sky Movies) at any time of the day. Viewers are required to enter their PIN to view. There should be a gentle transition to adult material, and 18-rated material is not allowed to be shown before 10:00 p.m.