Europe/London Sat Oct 26 23:00:00 1968 UT
Looks like isdst should be 1 on Europe/London Sat Oct 26 23:00:00 1968 and Europe/London Sun Oct 31 01:59:59 1971 zdump -v -c 1968,1973 Europe/London Europe/London -9223372036854775808 = NULL Europe/London -9223372036854689408 = NULL Europe/London Sun Feb 18 01:59:59 1968 UT = Sun Feb 18 01:59:59 1968 GMT isdst=0 gmtoff=0 Europe/London Sun Feb 18 02:00:00 1968 UT = Sun Feb 18 03:00:00 1968 BST isdst=1 gmtoff=3600 Europe/London Sat Oct 26 22:59:59 1968 UT = Sat Oct 26 23:59:59 1968 BST isdst=1 gmtoff=3600 Europe/London Sat Oct 26 23:00:00 1968 UT = Sun Oct 27 00:00:00 1968 BST isdst=0 gmtoff=3600 Europe/London Sun Oct 31 01:59:59 1971 UT = Sun Oct 31 02:59:59 1971 BST isdst=0 gmtoff=3600 Europe/London Sun Oct 31 02:00:00 1971 UT = Sun Oct 31 02:00:00 1971 GMT isdst=0 gmtoff=0 Europe/London Sun Mar 19 01:59:59 1972 UT = Sun Mar 19 01:59:59 1972 GMT isdst=0 gmtoff=0 Europe/London Sun Mar 19 02:00:00 1972 UT = Sun Mar 19 03:00:00 1972 BST isdst=1 gmtoff=3600 Europe/London Sun Oct 29 01:59:59 1972 UT = Sun Oct 29 02:59:59 1972 BST isdst=1 gmtoff=3600 Europe/London Sun Oct 29 02:00:00 1972 UT = Sun Oct 29 02:00:00 1972 GMT isdst=0 gmtoff=0 Europe/London 9223372036854689407 = NULL Europe/London 9223372036854775807 = NULL
Looks like isdst should be 1 on
Europe/London Sat Oct 26 23:00:00 1968
The convention is that if clocks are the same all year round and if this appears to be intended to be permanent, the isdst flag is zero even if the enabling legislation uses phrases like "daylight" or "summer". An example of that is the Turks & Caicos change in November. My vague impression is that that three-year period you're talking about was intended to be permanent. I haven't researched this, though.
As I understand it, Europe/London switched to a "permanent" one-hour offset from GMT on 1968-10-27; time was referred to as "British Standard Time" which, for better or worse, has the same BST abbreviation as "British Summer Time." Europe/London reverted to the "old" rules on 1971-10-31. My sense is that Paul is correct and that isdst should be 0 for the 1968-1971 period. @dashdashado On Mon, Sep 15, 2014 at 1:20 AM, Paul Eggert <eggert@cs.ucla.edu> wrote:
Looks like isdst should be 1 on
Europe/London Sat Oct 26 23:00:00 1968
The convention is that if clocks are the same all year round and if this appears to be intended to be permanent, the isdst flag is zero even if the enabling legislation uses phrases like "daylight" or "summer". An example of that is the Turks & Caicos change in November.
My vague impression is that that three-year period you're talking about was intended to be permanent. I haven't researched this, though.
On 2014-09-14 22:40, "" wrote:
Looks like isdst should be 1 on Europe/London Sat Oct 26 23:00:00 1968 and Europe/London Sun Oct 31 01:59:59 1971 zdump -v -c 1968,1973 Europe/London Europe/London -9223372036854775808 = NULL Europe/London -9223372036854689408 = NULL Europe/London Sun Feb 18 01:59:59 1968 UT = Sun Feb 18 01:59:59 1968 GMT isdst=0 gmtoff=0 Europe/London Sun Feb 18 02:00:00 1968 UT = Sun Feb 18 03:00:00 1968 BST isdst=1 gmtoff=3600 Europe/London Sat Oct 26 22:59:59 1968 UT = Sat Oct 26 23:59:59 1968 BST isdst=1 gmtoff=3600 Europe/London Sat Oct 26 23:00:00 1968 UT = Sun Oct 27 00:00:00 1968 BST isdst=0 gmtoff=3600 Europe/London Sun Oct 31 01:59:59 1971 UT = Sun Oct 31 02:59:59 1971 BST isdst=0 gmtoff=3600 Europe/London Sun Oct 31 02:00:00 1971 UT = Sun Oct 31 02:00:00 1971 GMT isdst=0 gmtoff=0 Europe/London Sun Mar 19 01:59:59 1972 UT = Sun Mar 19 01:59:59 1972 GMT isdst=0 gmtoff=0 Europe/London Sun Mar 19 02:00:00 1972 UT = Sun Mar 19 03:00:00 1972 BST isdst=1 gmtoff=3600 Europe/London Sun Oct 29 01:59:59 1972 UT = Sun Oct 29 02:59:59 1972 BST isdst=1 gmtoff=3600 Europe/London Sun Oct 29 02:00:00 1972 UT = Sun Oct 29 02:00:00 1972 GMT isdst=0 gmtoff=0 Europe/London 9223372036854689407 = NULL Europe/London 9223372036854775807 = NULL
The relevant rules, comments, and zones to examine in data/europe are: # Summer Time Order, 1968 (S.I. 1968/117) Rule GB-Eire 1968 only - Feb 18 2:00s 1:00 BST # The British Standard Time Act, 1968 # (no summer time) # The Summer Time Act, 1972 Rule GB-Eire 1972 1980 - Mar Sun>=16 2:00s 1:00 BST Rule GB-Eire 1972 1980 - Oct Sun>=23 2:00s 0 GMT and: # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Europe/London -0:01:15 - LMT 1847 Dec 1 0:00s 0:00 GB-Eire %s 1968 Oct 27 1:00 - BST 1971 Oct 31 2:00u which gives 1968 Oct 27 midnight as the transition from British Summer Time isdst=1 to British Standard Time isdst=0 both with GMT offset +1.00, from the British Standard Time Act 1968 c. 45, whichended itself effective 1971 Oct 31 2.00 GMT. See http://polyomino.org.uk/british-time and search for "1968 c. 45". -- Take care. Thanks, Brian Inglis
Perhaps we should document the alternative meaning of "BST" more clearly, as in the attached proposed patch.
Patch looks good. Was looking at this because Java (yes I know but...) thinks that Europe/London Sun Oct 31 01:59:59 1971 UT Is the following in Europe/London... 1971-10-31 02:59:59 GMT (+0100) Using SimpleDateFormat("yyyy-MM-dd HH:mm:ss z (ZZZZ)"); ... some sort of new definition of GMT... On 15 September 2014 18:09, Paul Eggert <eggert@cs.ucla.edu> wrote:
Perhaps we should document the alternative meaning of "BST" more clearly, as in the attached proposed patch.
participants (4)
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"" -
Arthur David Olson -
Brian Inglis -
Paul Eggert