1. Do I correctly understand that, under this proposal, IERS expects the civil authorities to change the local time zone every few thousand years so that the sun is roughly overhead at 12:00? (Assuming, of course, that the world keeps using local time long enough for this to be an issue.) 2. To correct some information you've received about UNIX: UNIX does not keep track of time in UTC. UNIX keeps track of time as an integer (plus, in some cases, a 6-digit or 9-digit fractional part) that counts seconds. The bulk of UNIX time-handling software simply adds or subtracts these integers to schedule or measure real-time events. The popular Olson tz library in ``right'' mode interprets the counter as the number of TAI seconds since 1970-01-01 00:00:10 TAI, and converts it to local time for human display, taking account of leap seconds. It can also convert from local time back to the counter. Many applications call this library. Unfortunately, previous time libraries didn't understand leap seconds--- UNIX predates leap seconds!---and this mistake was codified in the POSIX standard, along with an incorrect leap-year rule. There are still some programs that produce silly results during leap seconds. But they'll be fixed eventually. 3. The tz library won't work past 2038. I've been writing a new library intended to work until the Gregorian calendar is replaced. This code will, of course, be easier to write correctly if there are no more leap seconds. ---Dan