[LEAPSECS] A new use for Pre-1972 UTC

[Tony Finch]

On Tue, 17 Feb 2009, Gerard Ashton wrote:

>

>    Concatenate the "epoch" time at the time this ID value is being

>    generated ; the "epoch" time is the number of seconds elapsed since

>    00:00:00 Coordinated Universal Time (UTC) January 01,

>    1970 (not counting leap seconds)

>

> 2. It has all the problems of what UTC means before 1972 that have been

> discussed in this mailing list, as well as what kind of seconds are

> intended.


You can avoid that by specifying that the timescale can be any variant of
UT (UT1 or UTC or POSIX time, etc.) and is accurate to no better than a
second.

A better solution than a seconds count would be to use an ISO 8601 string.


> a. Rigorously defined epoch, rigorous definition of whether SI or UT1 second

> is used.


Don't bother worrying about what kind of seconds you have, because no
commodity computing environments do.


> c. Contains a minimal number of non-alphanumeric characters to facilitate

> parsing.


Punctuation is optional in ISO 8601.


> d. The same time will be represented identically,

> character-for-character, in all implementations.


Use ISO 8601 zulu time. You probably need to specify a strict profile, in
the manner of RFC 3339.

Tony.
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