of the element of surprise, overall hostility toward the format, and lack of media cross-promotion among them); some self-contained and personality-driven reality shows have been successfully rerun. Reruns of sports broadcasts, which face many of the same issues reality shows face, have found a niche, and networks such as MSG Network, ESPN Classic and NFL Network currently have a significant portion of programming time devoted to reruns of live sportscasts. DVD retail With the rise of the DVD video format, box sets featuring season or series runs of television series have become an increasingly important retail item. Some view this development as a rising new idea in the industry of reruns as an increasingly major revenue source in themselves instead of the standard business model as a draw for audiences for advertising. While there were videotape releases of television series before DVD, the format's limited content capacity, large size and reliance on mechanical winding made it impractical as a widespread retail item. Many series which continue to air first-run episodes (such as Modern Family and Grey's Anatomy) may release DVD sets of the prior season between the end of that season and the beginning of the next. Some television programs that are released on DVD (particularly those that have been out of production for several years) may not have all of the seasons released, either due to poor overall sales or prohibitive costs for obtaining rights to music used in the program; one such incidence is Perfect Strangers, which has seldom been in wide syndication since the late 1990s primarily due to lack of demand, which had only a DVD set of the first and second seasons released due to the expensiveness of relicensing songs used in later seasons of the series that are performed by the show's two lead characters. In some cases, series whose later season releases have been held up for these reasons may have the remaining seasons made available on DVD, often after a distributor that does not hold syndication rights to the program (such as Shout! Factory) secures the rights for future DVD releases. TV listings TV Guide originally used the term rerun to designate rebroadcast programs, but abruptly changed to repeat between April and May in 1971. Other TV listings services and publications, including local newspapers, would often indicate reruns as "(R)"; since the early 2000s, many listing services only provide a notation if