🚀 go-pugleaf

Jim,

Well, I suppose I should reveal why I chose the NTP format. The obvious
inference in DTS is that time began with the Gregorian Calendar, which
ticked the first on 15 October 1582. The Pope was a Catholic, of course,
and had little experience with time zones, leap seconds and the like,
and besides he was more concerned with Easter falling in the right
festival epochs. Moslems, Jews and Hindus probably have mixed feelings
on this particular choice, so I felt it not quite a terrific idea.

I chose 1 January 1900 simply because Jon Postel had preempted that
design choice in UDP/TIME and I wanted simple conversion. I could have
chosen the primal tick of the Julian Era, 4713 BC, but that's too many
bits and few cosmicologies twitch in periods that long. If I had it to
do again, I would choose 1 January 1872 when UTC itself was born. How
many leap seconds since 1582 anyway?

As to the choice of format (yawn), most time buzzards agree that 64
bits is about right, but to some epochs are more important than picoseconds
and to others the other way around. I was very concerned that high speed
nets that may come along be served, as well as time-transfer applications
in fields other than computer networking be served. Not the least
consideration was that the time format be easily cleaved into useful
chunks without requiring multiply/devide (read that process controllers
and PCs). The natural cleavage seemed to be seconds and fractions, which
leads to an LSB of an incredible 232 nanoseconds. According to journal
articles and sworn statements from my geodetic friends, this is about
the precision necessary to map the world, measure continental drift and
confirm global warming.

The question of epoch, so dear to many hearts, may be a red herring. There
are lots of other protocols, like my investment accounts, spreadsheets
and even other time protocols that have various degrees of Rolloveritis.
I even got a call from a NY Times reporter that wanted me to comment on
a report he heard that on 31 December 1999 the Social Security computers
would all stop and all retirees would starve. Now, it's highly unlikely that
many applications will find it necessary to determine precision intervals
spanning many years to a precision of 232 nanoseconds; but, if any do turn
up, they will need to account for leap seconds, which requires some kind
of institutional memory. If you have that, it's a simple matter to add
a leap-136-year bit to NTP and we all get well. 

My answer to all this is the Maya Long Count calender dating. The Maya
were the best timekeepers in the world and they kept the calender precise
for over a millenium. See the recent article in Scientific American.

Dave