X is a preeminent example of a band that’s gone “Beyond and Back” — to borrow one of their vintage song titles — but there’s always been an asterisk on the “back” part. There’s been no shortage of chances to see L.A.’s preeminent punk-era group on tour over the last 15 years, with the original lineup reunited and blazing through their most poetically rip-roaring catalog material from the late ‘70s and early ‘80s. But the setlists rarely if ever included anything post-1983. Coming up with any new material for X, as they have all along for their solo and side projects? Not even a consideration, seemingly.