Guardian Programmer's Guide

Managing Time
Guardian Programmer’s Guide — 421922-014
18 - 29
Interacting With the DST Transition Table
Interacting With the DST Transition Table
The daylight-saving-time (DST) transition table provides a way of indicating the time
and date at which transitions to and from daylight saving time will be made. On D-
series systems, you can set the DAYLIGHT_SAVING_TIME entry in the configuration
file to NONE, USA66, or TABLE during system generation. See the System Generation
Manual for details about the configuration file.
You can use the Subsystem Control Facility (SCF) to change the
DAYLIGHT_SAVING_TIME setting on your machine. The “SCF info subsys $zzkrn"
command shows the current setting for DAYLIGHT_SAVING_TIME (as well as the
TIME_ZONE_OFFSET). The "SCF alter subsys $zzkrn, DAYLIGHT_SAVING_TIME
TABLE" command changes the setting to TABLE. The change will take effect only at
the next system cold load. See the SCF Reference Manual for the Kernel Subsystem
for more information.
The following shows the result of setting the DAYLIGHT_SAVING_TIME entry to one of
the three available options:
For G04.00 and earlier G-series and D-series releases of the system, you can fill out
the DST transition table either interactively using the ADDDSTTRANSITION TACL
command, or programmatically using the ADDDSTTRANSITION procedure. You must
be a super-group user (255, n) to set information in the DST transition table.
For G05.00 and later G-series release systems, you can also delete an entry, modify
an entry, or get information about an entry in the DST table using the following
procedures: DST_TRANSITION_DELETE_, DST_TRANSITION_MODIFY_ and
DST_GETINFO_. For a description of the various error values returned by these
procedures, refer to the Guardian Procedure Calls Reference Manual.
DST_TRANSITION_ADD_ supersedes the ADDDSTTRANSITION procedure.
You must a super-group user(255, n) to use ADDDSTTRANSITION,
DST_TRANSITION_ADD_, DST_TRANSITION_DELETE_ or
DST_TRANSITION_MODIFY_.
If you choose to use the TABLE option, you must consider the following:
•
You must have at least one transition date that is less than the current date and
time, and at least two transition dates that are later than the current date and time.
•
Your first DST transition must be earlier than any date that will be referenced by
the BACKUP utility, any other utility, or application program.
NONE DST does not apply.
USA66 The system automatically follows the rules for daylight-saving-
time set for the United States by the Uniform Time Act of 1966.
TABLE You need to put entries into the DST transition table.