On 2015-02-13 12:54, Steve Allen wrote:
On Thu 2015-02-12T16:56:55 -0500, J William Piggott hath writ:
There are two separate databases in the zoneinfo system, posix and 'right'. 'Right' (now named leaps) includes leap seconds and posix does not.
To use the 'right' database the System Clock must be kept in UTC + leap_seconds, i.e., TAI - 10.
I would clarify that to read
To use the 'right' database the System Clock must count allseconds of UTC (and TAI), including leap seconds. From the beginning of 1972 onward this is equivalent to setting the System Clock to (TAI - 10 s).
This allows calculating the exact number of seconds between two dates that cross a leap second epoch.
I would clarify that to read
This means that the difference between two dates that span a leap second counts the number of seconds of TAI (and this is not congruent with POSIX).
The System Clock is then converted to the correct civil time, including UTC, by using the 'right' timezone files which subtract the leap sec- onds. Note: this configuration is considered experimental and is known to have issues.
Do astronomers or physicists keep their system clocks on TAI and use these right/leaps files? -- Take care. Thanks, Brian Inglis