SCTE 35 has been relied on for two decades by broadcasters and cable TV networks (“content providers”) to signal local avail breaks—the slots that are granted by the content providers to the cable system operators (and other multichannel video programming distributors) for local advertising. In the United States, these breaks are usually exactly a minute long and occur twice an hour. The content providers usually schedule promos and other non-essential filler material in these slots for cable operators to insert their local commercials over. Local commercial insertion is a mature business (and a very big business).
Bringing Order to the SCTE 35 Chaos