[LEAPSECS] Lets get REAL about time.

[Warner Losh]

On Jan 24, 2012, at 4:51 PM, Mark Calabretta wrote:


> 

> On Tue 2012/01/24 16:23:17 PDT, Warner Losh wrote

> in a message to: Leap Second Discussion List <leapsecs at leapsecond.com>

> 

>>> In the latter, the second hand would move continuously past 60 to 01

>>> second and immediately flick back to 60, thus making it possible to

>>> reckon time during a leap second.

>> 

>> Or it could move from 00 back to 59...

>> 

>> And the number of choices here is illustrative of the implementation

>> details elsewhere :)

> 

> TF460-6 specifies that time during a leap second be represented as,

> for example, 23:59:60.7, which suggests to me that the second hand

> should move past 60 to "61".



But then it would be in the wrong minute.

What's the right answer: both.  The standard is silent on the issue since there is no '60' on the clock.  One can get the minute and hour wrong by repeating the first 6-degrees of the dial and have the 'wrap' be like you suggest.  One can get the minute and hour right, but with a less "modulus"ly beautiful 60 - 00.

There's no standard for mapping a non-uniform radix onto a uniform-radix device.  Implementations on POSIX time_t based systems suffer similar ambiguity.

Warner