A method of generating a program signal stream comprises creating a sequence of serial programs that include a first event and a second, later occurring event and inserting a plurality of messages in the sequence of serial programs, between the first event and the second event. The messages may be indicative of a time to the second event, as measured from each respective message of an elapsed time since the first event, to each respective message. Alternatively or in addition, the messages may be at equal time intervals between the first event and second events. The first and second events may be the start and end of a program or a program portion, such as a chapter, an advertisement, unscheduled content or an entire program, for example. At least one message indicative of the time to the second event may be inserted in the sequence of serial programs prior to the first event.