Wise ones of the TZ list, A (quite academic, but possibly interesting) question came up here as we're trying to document the behaviour of our time zone code. We're trying to figure out whether the transition time is reached or skipped. For example, for these 2 rules, # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule TC 1979 1986 - Apr lastSun 2:00 1:00 D Rule TC 1979 2006 - Oct lastSun 2:00 0 S does the clock reach "2:00" on the transition days? In that case, the transition would go from "2:00(S)" -> "3:00(D) + epsilon" when moving forward, and "2:00(D)" -> "1:00(S) + epsilon" when moving back. Or does it go from "2:00(S) - epsilon" -> "3:00(D)" and "2:00(D) - epsilon" -> "1:00(S)" ? If the transition time IS reached, which "name" would attach to it? Phrased differently, for the Americas/NewYork transitions this spring: 1) Is the time coordinate value at the instant of transition "2:00 AM" or "3:00 AM" (NIST says "begins at 2:00 a.m. on the second Sunday of March") 2) Is the designation of that coordinate (in the local New York City timezone) "EDT" or "EST"? Thanks! Mike