On 1/3/2017 12:34 PM, Tony Finch wrote: > > Joe Touch <touch@xxxxxxx> wrote: > > We really need to separate the frames of reference of time - there's no > > need for smear for internal "seconds since epoch" time. > > Well, the problem is that "seconds since the epoch" is not a count of > UTC seconds, Correct; it's UTC-(leap seconds since epoch start). > it is a mapping from broken-down time to a linear time, Seconds since epoch is as linear as it gets. > and the mapping is defined in a way that requires 86400 seconds per > day and does not accommodate leap seconds. The conversion of epoch seconds to larger units is where the leap seconds is counted. A "day" as a unit of time is not exactly 86400 seconds (if it were, we wouldn't need leap seconds). > http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_16 > > Leap smear exists mainly because "seconds since the epoch" does not > allow for leap seconds. Seconds since epoch is unambiguous and linear. It is in the conversion to other representations or aggregations where leap seconds needs to be considered. Joe