The following issue has been SUBMITTED. ====================================================================== https://www.austingroupbugs.net/view.php?id=1788 ====================================================================== Reported By: Guy Harris Assigned To: ====================================================================== Project: 1003.1(2016/18)/Issue7+TC2 Issue ID: 1788 Category: Base Definitions and Headers Type: Clarification Requested Severity: Comment Priority: normal Status: New Name: Guy Harris Organization: User Reference: Section: N/A Page Number: N/A Line Number: N/A Interp Status: --- Final Accepted Text: ====================================================================== Date Submitted: 2023-11-18 00:16 UTC Last Modified: 2023-11-18 00:16 UTC ====================================================================== Summary: The meaning of "Daylight Saving Time" should be clarified Description: The term "Daylight Saving Time" is used in a number of places in the specification.
In much of the world, it refers to the time during the summer when clocks are turned forward from standard time. However, in some locations, such as Ireland, "standard time" is observed during the summer, and the clocks are turned backward during the winter. At least some web sites in Ireland refer to "Daylight Saving Time" as the time when clocks are not turned backward. Furthermore, in Namibia, a change was made to turn clocks backward during the winter, and at least one news site referred to the time when clocks are turned backward as "Daylight Saving Time". This could lead different readers of the specification to reach different conclusions as to what is done to clocks when Daylight Saving Time is in effect. The specification of the TZ environment variable in section 8.3 Other Environment Variables allows the UTC offset if Daylight Saving Time is in effect either to be more than or less than the UTC offset if Daylight Saving Time, so it appears that the intent is to allow Daylight Saving Time either to be "summer time" or "winter time". Desired Action: The document should, at minimum, explicitly state that, if Daylight Saving Time is in effect, the clock may have its offset from UTC either be more than, or less than, its offset from UTC when Daylight Saving Time is not in effect. Ideally, it should either define, in some fashion, what "standard time" and "Daylight Saving Time" are, or explicitly indicate that the meaning is either implementation-defined or undefined, so that code makes no invalid assumptions about, for example, the significance of the tm_isdst member of a struct tm being set to a positive value by localtime(). ====================================================================== Issue History Date Modified Username Field Change ====================================================================== 2023-11-18 00:16 Guy Harris New Issue 2023-11-18 00:16 Guy Harris Name => Guy Harris 2023-11-18 00:16 Guy Harris Section => N/A 2023-11-18 00:16 Guy Harris Page Number => N/A 2023-11-18 00:16 Guy Harris Line Number => N/A ======================================================================