It seems the meaning of the term "Standard time" in common-use and in
POSIX is in conflict with the definitions in ISO 8601 and IEC 60050-111.
Wikipedia (not always an authoritative source)
Standard time
http://en.wikipedia.org/wiki/Standard_time
states:
"Where daylight saving time is used, the term standard time typically
refers to the time without the offset for daylight saving time.".
That is consistent with my understanding of "Standard time".
POSIX doesn't seem to explicitly state this, but the logic of the TZ
environment and functions are consistent with this definition.
But ISO 8601 and IEC 60050-111 say "standard time" may include time
shifts for "winter time" and "summer time":
In ISO 8601 ----------------
2.1.14
standard time
time scale derived from coordinated universal time, UTC, by a time shift
established in a given location by the
competent authority
[IEC 60050-111]
NOTE This time shift may be varied in the course of a year.
2.1.15
standard time of day
quantitative expression marking an instant within a calendar day by the
duration elapsed after midnight in the
local standard time
[IEC 60050-111]
NOTE Standard time of day is called “clock time” in IEC 60050-111.
In IEC 60050-111 ---------------
111-16-16
standard time
time scale derived from coordinated universal time, UTC, by a time shift
established in a
given location by the competent authority
NOTE Examples are Central European Time (CET), Central European Summer
Time (CEST), Pacific
Standard Time (PST), Japanese Standard Time (JST), etc.
111-16-17
clock time
quantitative expression marking an instant within a calendar day by the
duration elapsed after
midnight in the local standard time
NOTE Usually, clock time is represented by the number of hours elapsed
after midnight, the number
of minutes elapsed after the last full hour, and, if necessary, the
number of seconds elapsed after the
last full minute, possibly with decimal parts of a second. Examples of
the standardized representation
(see ISO 8601) are 09:01; 09:01:12; 09:01:12,23.
-----------
Is my interpretation correct? Can anyone shed light on how and why ISO
8601 and IEC 60050-111 are in conflict with common use and POSIX and how
this may have come about?
-Brooks
_______________________________________________
LEAPSECS mailing list
LEAPSECS@leapsecond.com
http://six.pairlist.net/mailman/listinfo/leapsecs
