Issue 16682: Date-Time Issue: Time Zones (date-time-ftf) Source: NIST (Mr. David Flater, dflater(at)nist.gov) Nature: Uncategorized Issue Severity: Summary: 13.5.4 "When there are two calendars for a time zone, one is standard time and the other is daylight savings time. The dates and time of day for changing between them is determined by local authorities for each time zone." Said authorities do, on occasion, change not only the dates and time of day for changing between local calendars, but the time offsets that apply within a locale. I would like to see the example that demonstrates how this specification would be used to reason coherently about events both prior to and after such a time zone transition in a continuously operating system (no big-bang updates allowed). Comment #2 The Annex B references do not include the Zoneinfo database, ftp://elsie.nci.nih.gov/pub/, http://en.wikipedia.org/wiki/Tz_database. (Zoneinfo handles the situation mentioned in Comment #1 by making the locale identifier be the primary key. For example, if your time zone is America/New_York, then the different rules for Daylight Savings Time before and after the 2007 changeover are implicit in any conversion between local time and universal time.) Resolution: Revised Text: Actions taken: November 16, 2011: received issue Discussion: End of Annotations:===== MG Issue No: 16682 Title:Time Zones Source: David Flater . NIST . dflater@nist.gov Summary: Comment #1 13.5.4 "When there are two calendars for a time zone, one is standard time and the other is daylight savings time. The dates and time of day for changing between them is determined by local authorities for each time zone." Said authorities do, on occasion, change not only the dates and time of day for changing between local calendars, but the time offsets that apply within a locale. I would like to see the example that demonstrates how this specification would be used to reason coherently about events both prior to and after such a time zone transition in a continuously operating system (no big-bang updates allowed). Comment #2 The Annex B references do not include the Zoneinfo database, ftp://elsie.nci.nih.gov/pub/, http://en.wikipedia.org/wiki/Tz_database. (Zoneinfo handles the situation mentioned in Comment #1 by making the locale identifier be the primary key. For example, if your time zone is America/New_York, then the different rules for Daylight Savings Time before and after the 2007 changeover are implicit in any conversion between local time and universal time.) Resolution: To: date-time-ftf@omg.org Subject: DTV Issue 16682 - Title:Time Zones X-KeepSent: 46B6CF9D:037F1982-85257A8A:006A1341; type=4; name=$KeepSent X-Mailer: Lotus Notes Release 8.5.3 September 15, 2011 From: Mark H Linehan Date: Mon, 1 Oct 2012 15:19:51 -0400 X-MIMETrack: Serialize by Router on D01MC604/01/M/IBM(Release 8.5.3FP2IF1|July 25, 2012) at 10/01/2012 15:19:52 x-cbid: 12100119-8974-0000-0000-00000EBFC389 X-IBM-ISS-SpamDetectors: X-IBM-ISS-DetailInfo: BY=3.00000294; HX=3.00000196; KW=3.00000007; PH=3.00000001; SC=3.00000008; SDB=6.00178958; UDB=6.00040529; UTC=2012-10-01 19:20:22 Proposed resolution: ----------------------------- Mark H. Linehan STSM, IBM Research Date-Time Issue 16682 - time zones.doc Disposition: Resolved OMG Issue No: 16682 Title:Time Zones Source: David Flater . NIST . dflater@nist.gov Summary: Comment #1 13.5.4 "When there are two calendars for a time zone, one is standard time and the other is daylight savings time. The dates and time of day for changing between them is determined by local authorities for each time zone." Said authorities do, on occasion, change not only the dates and time of day for changing between local calendars, but the time offsets that apply within a locale. I would like to see the example that demonstrates how this specification would be used to reason coherently about events both prior to and after such a time zone transition in a continuously operating system (no big-bang updates allowed). Comment #2 The Annex B references do not include the Zoneinfo database, ftp://elsie.nci.nih.gov/pub/, http://en.wikipedia.org/wiki/Tz_database. (Zoneinfo handles the situation mentioned in Comment #1 by making the locale identifier be the primary key. For example, if your time zone is America/New_York, then the different rules for Daylight Savings Time before and after the 2007 changeover are implicit in any conversion between local time and universal time.) Resolution: Revised Text: (All references are to the beta-2 document.) In clause 10.3, add a Note and Example to the end of the glossary entry for 'local calendar': Note: Time references that are intended to be independent of changes to local calendars should be specified as UTC and a time offset. Example: Most locations in the United States change between daylight time and summer time twice a year, and the specifications for when the changes happen have themselves changed on occasion. To specify noon in NY independent of local calendar, use '12:00 UTC.5:00'. In clause 10.3, add a Note to the end of the glossary entry for 'time zone': Note: The Time Zone Database [Zoneinfo] documents the history of local time for many locations. It is updated periodically to reflect changes made by political bodies to time zone boundaries, UTC offsets, and daylight-saving rules. Add a reference to Annex B, in the appropriate alphabetical position: Zoneinfo Olson, Ted and the International Assigned Numbers Authority (IANA), Time Zone Database, available at http://www.iana.org/time-zones Disposition: Resolved