a resulting significant loss of advertising revenue—not only allowed television stations to claim local exclusivity over syndicated programs (even if the out-of-market station has the same owner as the station with that particular exclusive program) and required cable systems to black out claimed programs; it also granted cable systems or carrier firms the ability to secure an agreement with the claimant station or a syndication distributor to continue carrying a claimed program through an out-of-market station, allowing some superstations to acquire partial or exclusive national cable rights to certain programs. The law also closed the terrestrial loophole that allowed superstations like WGN and WTBS to continue paying local single market rates for programming acquisitions even as they were gaining national coverage, whilst selling that extended coverage to advertisers; this change made it so that other local stations which had their signals beamed to a satellite transponder – whether willingly or not – were charged appropriately for program content based on their actual national distribution, depending on arrangements with any given syndicator. A major concern brought about by the new rules was that it would force cable systems to drop certain superstations altogether, rather than shoulder expenses that would be incurred with the resultant blackouts and any responsibilities for acquiring substitute programming, thereby denying viewers access to sporting events popular among subscribers who received those signals. In preparation for the policy's implementation – which took effect on January 1, 1990, after FCC-enforced delays in the regulation's rollout – some superstations decided to indemnify cable systems from potential blackouts by ensuring that, at least, some programs that could be subjected to local syndication exclusivity claims could continue to be shown to their national audience, so as to prevent the loss of sports access. WTBS effectively limited the number of necessary blackouts or substitutions by licensing the majority of its programming for carriage on both its national and Atlanta area feeds. (Certain local programs carried by the station, such as public affairs and educational children's programs, were not carried on the TBS national feed, but these omissions were because those programs were strictly intended to fulfill local obligations for public affairs content.) United Video and Eastern Microwave respectively opted to devise standalone national feeds of WGN and WWOR, each incorporating an alternate schedule differing from the local broadcast signal to some degree—comprising both programs aired by the parent station for which the companies