> Still, it's a strange assumption, given that TF.640 allows, I > understand, leaps at the end of any month. Unofficially, the > wording seems to be: > > > A positive or negative leap-second should be the last second > > of a UTC month, but first preference should be given to the end > > of December and June, and second preference to the end of March > > and September. > > Anybody got access to a proper copy and can say whether that's > right or not? If it is right then the Wikipedia article on leap > seconds needs fixing.
The above is a direct quote from ITU-R-TF.460-4, annex I, section D.2.1. Secont D.2.3 is the one that many people here would like to change in some way, usually the time period: "The IERS should decide upon and annoucne the introduction of a leap-second, such an announcement to be made at least eight weeks in advance." Which many people would like see extended to a number of years. Heck, a simple step would be to announce every 6 months the leap seconds for a year, but I'll bet even that step would be politically difficult. Curiously, BIH is currently, at least in the document I have, expected to predict what the value of DUT1 is to .1 second at least a month in advance so that frequency standard broadcasts can prepare for changes of this value a month in advance. There's an exception for IERS to step in two weeks in advance if the earth's rotation rate hickups. Warner