 As individual broadcasters are subject to a market cap limit to prevent concentration of media ownership, O&O stations are typically limited to key markets; the remainder of the network consists of affiliates owned by third-party broadcasters independent from the network's owner (including companies such as Hearst Television, Nexstar Media Group, and Tegna, Inc. among others).Networks typically restrict a media market (as defined by the Nielsen Company) to one affiliate each, but there have been grandfathered exceptions in certain markets due to historical precedents (such as an affiliate whose signal did not sufficiently cover the entirety of the market in the era of analog television—such as the cases of the ABC affiliates WZZM/Grand Rapids and WOTV/Battle Creek, and the fellow pair of WFTS-TV/Tampa and WWSB-TV/Sarasota—as the signal of present-day CBS station WTSP was short-spaced in order to protect Miami's ABC affiliate WPLG, which broadcast on the same frequency).Besides considerations for time zones, especially in regards to live programs and how they may impact scheduling of other programming, the schedule of network programming is generally consistent between affiliates.