This section contains an overview of time zones as implemented by Calendar Server software.
The timezones.ics file contains the representation of the time zones supported by Calendar Server. The file is located in the following directory:
At startup, Calendar Server reads the timezones.ics file, generates time-zone data, and then stores the data in memory. Thus, time-zone data is kept in memory while Calendar Server is running. Consequently, if you add a new time zone or modify an existing one, you must stop and restart Calendar Server for the change to take effect.
Time zones in the timezones.ics file are identified by the TZID parameter. For example, Calendar Server identifies the Pacific Standard Time (PST/PDT) zone using the America/Los_Angeles TZID, as shown in Example 19–1. The TZNAME property is an abbreviated representation of the time zone, such as PST (Pacific Standard Time) for the America/Los_Angeles time zone.
Time zones such as America/Los_Angeles that recognize daylight savings time (DST) contain two subcomponents: STANDARD for standard time and DAYLIGHT for DST. The X-NSCP-TZCROSS list contains a series of dates that indicate when the time zone changes to and from DST (DAYLIGHT) and standard (STANDARD) time.
The RRULE property defines the pattern of the STANDARD and DAYLIGHT rules. The TZOFFSETFROM and TZOFFSETTO properties define the offset from GMT before and after the DST to standard or standard to DST change occurs. The Communications Express user interface uses the dates in X-NSCP-TZCROSS to determine when to display a change in the time zone.
A WCAP command that includes the time zone ID (tzid) parameter should refer to a valid time zone defined in the timezones.ics file. Calendar Server then returns data using that time zone. If a WCAP command specifies an unrecognized time zone, Calendar Server returns data in the GMT time zone by default. For more information about WCAP, refer to theSun Java System Calendar Server 6.3 WCAP Developer’s Guide.
The following example shows the America/Los_Angeles time zone representation in the timezones.ics file.