PBS World, the digital doc and pubaffairs channel, goes national today on 55 stations representing 24 licensees reaching more than 27 percent of U.S. households, according to its producers. The channel, produced by PBS, Boston’s WGBH and New York’s WNET in partnership with American Public Television and NETA, features time-shifted signature pubTV offerings including Frontline, The NewsHour and Nova (schedule PDF) . John Boland, PBS content chief, discussed the channel at some length in a May Q&A. Also earlier this year: David Liroff, CPB senior v.p. for media strategy, discussed in a Current commentary how stations balance bandwidth limitations with the increasing abundance of high-def and multicast program options, which include other national streams such as Create and Spanish-language V-Me. (Liroff was WGBH’s v.p. and chief tech officer when he wrote his commentary.)