[LEAPSECS] Civil timekeeping before 1 January 1972

[Tom Van Baak]

> leap59 and leap61 are Leap Second announce signals, set 12 hours prior 
> to the insert. There has been discussion about when the official 
> announcements and expiration should be announced. ITU Rec 460 says 
> "...at least eight weeks in advance". PTP can't do that, a point to keep 
> in mind.

You've got to be kidding. Who on earth decided on only 12 hours notice? And 8 weeks is wrong too, for a different reason.

You can have 8 weeks of notice (or 6 months or 100 weeks) as long as you are given the actual future date of the leap second, as is done with GPS. You can get away with single warning bits too, as long as they apply to current month only, as is done with WWVB. Both of these are models on how to send out leap second notifications correctly. But allowing 8 weeks without a way to know which month it will occur in is wrong. For bit-only leap second warnings 4 weeks is the limit.

/tvb