During my time (1979-1982) as a master control operator at WLKY-TV in Louisville (then ABC, now CBS), the period from 3:57:30 PM (the end of "General Hospital") until 5:59:00 PM, EDT/EST (the countdown into the first, live feed of "ABC World News Tonight") Monday-Friday was ABC Network-to affiliate closed circuit time, available to affiliates for local programming. These were the days of the split anchor news shows with Frank Reynolds in New York and Max Robinson in Chicago, with Peter Jennings as a frequent contributor, relief anchor, and later as the regular London reporter.
I remember the ABC announcer at 4:00 PM every day-"Hello stations, this is your American Broadcasting Company affiliate service feed for (day-date), and is NOT-repeat-NOT for broadcast live. Be sure this feed does not retransmit live to your viewers."
During this closed-circuit time, the stations would receive and record telescoped feeds of prime-time programs, regionalized commercials, timing cards for upcoming programs such as "20/20," and the Daily Electronic Feed (ABC-DEF, as it was nicknamed) of news packages, newstape and film for local VO, weather, sports and net promos. WLKY's early local news hit at 5:30 PM, leading into the live "A Feed" of ABC News at 6:00:00 PM ET. Access syndication started at 6:30:30 with Barry/Enright's revived "Tic Tac Dough."