 Where the usual slice operators mean (as the eternalist would put it) “at some past (or future) moment”, a span operator means “at some past (or future) interval” ([Lewis] 2004: 12). Thus, where “it HAS been that” is the past-tense span operator, Lewis suggests that we translate “there have been two kings named Charles” as “it HAS been that (there are two kings named Charles)”. By eternalist lights, this means that “it is true of some interval in the past that there are two kings named Charles” ([Lewis] 2004: 12). The presentist, of course, cannot accept this translation, but must presumably treat span operators as primitives. (2007: 73)