M. Warner Losh wrote: > In message: <[EMAIL PROTECTED]> > Rob Seaman <[EMAIL PROTECTED]> writes: > : On Jan 31, 2007, at 8:52 PM, M. Warner Losh wrote: > : > : > and 13 times when a leap second could have been inserted, but wasn't > : > :-) > : > : Make that 1 out of 84 opportunities by the standard as written. > > Well, bulletin C says: > > Leap seconds can be introduced in UTC at the end of the months of December > or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every > six months, either to announce a time step in UTC, or to confirm that there > will be no time step at the next possible date. > > which is what I based my statement on. The standard says that June > and December are primary, and March and October are secondary times > for a leap second. Much of the gear in the field handles Jun/Dec OK. > Some handles Mar/Oct. But much of it won't handle Mar/Oct or other > months. ntpd handles only June/December. This whole monthly thing, > while technically allowed in the UTC standard, as a practical matter > won't happen for a long, long time. Even when the quadratic nature of > leapseconds causes their frequency to be more often, I suspect a > different mechanism will need to be in place. > > Warner > >
The "standard," however, is not Bulletin C, but ITU-R Recommendation TF.460-4, which reads (Annex I, section D.2.1): "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." -- James Maynard Salem, Oregon, USA _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
