Daylight Saving Time

(What is it and why do we do it?)

Setting Time Zone Information on OpenVMS Alpha Version 7.2-1 and earlier:

·        Start Daylight Saving Time (forward one hour)

·        End Daylight Saving Time (back one hour)

Setting Time Zone Information on OpenVMS Alpha Version 7.3 and later.

Start Daylight Saving Time:

To set your system's time FORWARD one hour to start Daylight Saving Time,

run the following job:

$ @sys$examples:daylight_savings.com

      This procedure queues a batch job which changes the system time

      and system timezone differential around a daylight savings time

      change. Enter a '?' at any time for help, hit control-c to exit.

      The Time Differential Factor (TDF) is the difference

      between your system time and Coordinated Universal Time (UTC).

      The difference is expressed in hh:mm format. The Americas

      have negative offsets from UTC, while Europe, Africa, Asia

      and Australia have positive offsets from UTC.

* Enter the Time Differential Factor:    -4:00

      If this is a seasonal time change, it may also be

      necessary to modify the system time. Generally,

      seasonal time changes result in adding 1:00 hour,

      or adding -1:00 hour to the local time.

* Do you wish to modify the local system time [N]:    Y

      Enter the time value you would like to add to

      the local time. The value can be a positive or

      a negative (-hh:mm) value.

* Enter the time value:    +1:00

      The process to modify your timezone offset and local

      time (if supplied) can occur now or in the future.

      Enter <ret> to run the job now.

* Enter the run time in the DD-MMM-YYYY:HH:MM:SS format:    07-APR-2002:02:00:00

      NEW SYSTEM TIME DIFFERENTIAL FACTOR = -4:00.

      ADDING +1:00 TO THE LOCAL TIME.

      JOB RUN TIME : 07-APR-2002:02:00:00

* Continue? [Y]:    Y

      Job DST_CHANGE (queue SYS$BATCH_MYALPHA, entry 120) holding until 07-APR-2002 02:00

      Batch Job DST_CHANGE scheduled to run at 07-APR-2002:02:00:00

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End Daylight Saving Time:

To set your system's time BACK one hour to end Daylight Saving Time,

run the following job:

$ @sys$examples:daylight_savings.com

        This procedure queues a batch job which changes the system time

        and system timezone differential around a daylight savings time

        change.  Enter a '?' at any time for help, hit control-c to exit.

        The Time Differential Factor (TDF) is the difference

        between your system time and Coordinated Universal Time (UTC).

        The difference is expressed in hh:mm format.  The Americas

        have negative offsets from UTC, while Europe, Africa, Asia

        and Australia have positive offsets from UTC.

* Enter the Time Differential Factor:    -5:00

        If this is a seasonal time change, it may also be

        necessary to modify the system time.  Generally,

        seasonal time changes result in adding 1:00 hour,

        or adding -1:00 hour to the local time.

* Do you wish to modify the local system time [N]:    Y

        Enter the time value you would like  to add to

        the local time.  The value can be a positive or

        a negative (-hh:mm) value.

* Enter the time value:    -1:00

        The process to modify your timezone offset and local

        time (if supplied) can occur now or in the future.

        Enter <ret> to run the job now.

* Enter the run time in the DD-MMM-YYYY:HH:MM:SS format:   28-OCT-2001:02:00:00

        NEW SYSTEM TIME DIFFERENTIAL FACTOR = -5:00.

        ADDING -1:00 TO THE LOCAL TIME.

        JOB RUN TIME : 28-OCT-2001:02:00:00

* Continue? [Y]:  Y

        Job DST_CHANGE (queue SYS$BATCH_MYALPHA, entry 120) holding until 28- OCT-2001 02:00               

        Batch Job DST_CHANGE scheduled to run at 28-OCT-2001:02:00:00

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