 Complete the following phrase:  Fox, who started covering NASCAR in 2001, resisted the use of the technology for many years. By about 2010, however, executives began exploring the concept. In 2011, they conducted one experimental commercial break with a split-screen format. Through 2011, Fox has preferred to air traditional, full-screen commercials, and if any action occurs during the break, their policy is to interrupt the commercial and return to the live action e.g. at the 2013 Auto Club 400, the broadcast was in a commercial break when Clint Bowyer blew an engine and spun, so the feed immediately cut the commercial break right away; at the 2013 Aarons 499, the feed was in commercial break when a crash occurred on lap 43. FOX returned to using the side-by-side coverage during the 