Episodes usually have a running order. In a news programmes these might be individual new stories, in a music programme the tracks played, in a football programme the matches covered. In PIPs the running order is modelled as a set of segments hanging off an episode version. Because a version can have many segments and a segment can be used in many versions, segments are joined to versions via segment events. Segment objects describe the editorial content of the segment and its duration. Segment events describe where the segment occurs in the version either by position (this is the third segment) or by the offset start time (how many seconds into the version the segment starts). This allows for segment reuse between different versions of the same episode or different versions of different episodes. So a segment of the canonical version of a Top Gear episode might be a review of a Ferrari and that same segment might be reused in the canonical version of the Top Gear Christmas special or might be reused in the canonical version of a clip...