HP OpenVMS Systems Documentation

DECdts binary time values are based on Coordinated Universal Time (UTC), an international time standard that has largely replaced Greenwich Mean Time (GMT) as a reference. For most measurement purposes, UTC is the equivalent of GMT. However, time zones are still determined by their relationship to the prime meridian in Greenwich, England. The local time in each time zone or locale is determined by its offset, or differential, from the Greenwich time zone. This value is commonly expressed as a time differential factor (TDF) of a positive or negative number of hours.

3.7.1 Selecting the DECdts Configuration Option

To reconfigure DECdts, proceed as follows from the Configuration Options menu:

* Which configuration option to perform?            [1] :5

Select Option 5 and press Return.

The system displays:

 DTSS$CONFIG-I-LOGS Deassigning system timezone logicals

 DTSS$CONFIG-I-STOPDTS  Deleting the DTSS Entity

 Node 0 DTSS
 at 1995-08-04-18:36:19.740+00:00Iinf

 Node 0 DTSS
 at 1995-08-04-18:36:23.960+00:00Iinf

        Timezone Options:

        [0]     Exit Timezone Configuration

        [1]     Choose a timezone using menus
        [2]     Use Universal Coordinated Time (UTC)
        [3]     Type in your own timezone rule

* Enter an option number                            [1] :

The following sections explain each of the DECdts menu options.

When you are initially configuring a system, you must determine its geographical location and designate its time zone rule (TZR), which is based on the location. The TZR contains the abbreviated name of the system's time zone and the applicable TDF, so that DECdts can calculate UTC from the system (local) time during the initial configuration of the DECdts software. The TZR also contains information on any seasonal adjustments to the TDF that normally apply in the selected time zone.

If you want to select the commonly accepted TZR for a given area and system, you can use the net$configure procedure menus to select the geographical location of the system. Based on your selection, the net$configure procedure automatically sets the TZR. After you configure your system, it displays the local time even though the DECdts software uses UTC in the background. Because the default value of the DECdts management attribute Automatic TDF Change is TRUE, DECdts also changes the displayed local time automatically if there is a seasonal adjustment to the system's TDF.

In rare instances, you may want to customize the TZR for your system, thereby modifying its TDF from the one that normally applies in a given time zone or location. The net$configure menus also provide a selection for entering a custom TZR for your system, although you must know the TZR syntax to enter it. See Section 3.7.2.3 for further information on customizing the system's TZR.

After the initial system configuration, you can reconfigure the system's time zone rule (TZR) by selecting Option 5 in the top-level net$configure menu. For example, this may be necessary because you moved the system to a different location. To reconfigure the TZR, you must know the system's geographical location, or in some cases, the time zone. If you do not know the system's time zone and the configuration procedure requires you to enter it for your locale, refer to the world time zone map in the DECnet-Plus DECdts Management guide. Additionally, when you reconfigure the DECdts software, you are given the option of setting the system's time to UTC time or customizing the system's time to any time zone.

3.7.2.1 Configuring Your System's Local Time Using Menus (Menu Option 1)

Option 1 of the Timezone Options menu allows you to choose the geographical region and conventional TZR for the system. DECdts uses the TZR to automatically convert UTC to the local time whenever the time is displayed. To use Option 1, proceed as follows:

* Enter an option number                           [1] :

Press Return to select Option 1.

The procedure displays a menu of continental regions:

         Timezone Region Options:

        [0]     Return to the Timezone Options menu

        [1]     Europe
        [2]     North America
        [3]     Central & South America
        [4]     Africa
        [5]     Asia
        [6]     South Pacific
        [7]     Antarctica

* Enter a timezone region number                        :2

Enter the option number for the region where the system resides and press Return, or return to the previous menu by typing 0.

If you select a region, the procedure displays a menu of subregions within the region you select. The subregion you select determines the time zone rule for the system. For example, if you enter Option 2 (North America), the procedure displays the following menu:

         Timezone Subregion Options:

       [0]     Return to Region Options menu

       [1]     US/Eastern
       [2]     US/East-Indiana
       [3]     US/Central
       [4]     US/Mountain
       [5]     US/Pacific
       [6]     US/Alaska
       [7]     US/Arizona
       [8]     US/Navajo
       [9]     US/Michigan
       [10]    US/Aleutian
       [11]    US/Hawaii
       [12]    US/Samoa
       [13]    Canada/Newfoundland
       [14]    Canada/Atlantic
       [15]    Canada/Eastern
       [16]    Canada/Central
       [17]    Canada/East-Saskatchewan
       [18]    Canada/Mountain
       [19]    Canada/Pacific
       [20]    Canada/Yukon

* Enter a timezone subregion number                   : 1

Enter the option corresponding to the subregion where the system resides; in the example, the system is in the eastern United States. After you make a selection, the procedure executes and displays information on the NCL DTSS module subroutines that initialize the DECdts software with the new settings:

DTSS$CONFIG-I-LOGS Defining system timezone logicals
DTSS$CONFIG-I-SETLCL Setting Local Clock
%RUN-S-PROC_ID, identification of created process is 00000059

Node 0 DTSS
at 1995-02-25-08:17:29.520-05:00Iinf

Node 0 DTSS
at 1995-02-25-08:17:30.790-05:00Iinf

Node 0 Event Dispatcher Outbound Stream *
at 1995-02-25-08:17:30.950-04:00Iinf

Node 0 DTSS
at 1995-02-25-08:17:39.978-05:00I0.327

Node 0 DTSS
at 1995-02-25-08:17:45.868-05:00I0.328

Characteristics

   Automatic TDF Change = True

Node 0 DTSS
at 1995-02-25-08:17:51.898-05:00I0.328

DTSS$CONFIG-I-STARTDTS Restarting the DTSS Entity
%RUN-S-PROC_ID, identification of created process is 0000006B

Node 0 DTSS
at 1995-02-25-08:18:06.138-05:00Iinf

Node 0 DTSS
at 1995-02-25-08:18:07.488-05:00Iinf

Node 0 Event Dispatcher Outbound Stream *
at 1995-02-25-08:18:08.560-04:00Iinf

This completes changes to DECdts configuration using Option 1.

3.7.2.2 Configuring Your System's Local Time as UTC (Menu Option 2)

If your system is located in the GMT time zone or Antarctica, and you do not want to make seasonal adjustments to the TDF, you may want to use UTC as your system's local time. You can also configure all network systems with UTC if you consider local time irrelevant for your applications. If you select UTC as the local time and later enter the NCL command show dtss current time, the local time displayed has a TDF of 0 (zero).

The following example shows how to select UTC for the system's local time.

         Timezone Options:

        [0]     Exit Timezone Configuration

        [1]     Choose a timezone using menus
        [2]     Use Universal Coordinated Time (UTC)
        [3]     Type in your own timezone rule

* Enter an option number                            [1] :2

The net$configure procedure allows you to create a customized time zone rule (TZR) for your system, rather than selecting a location and having the procedure configure a TZR for you. When you create a customized TZR, you must supply the correct abbreviation for the system's time zone, the zone's offset from GMT, and optional seasonal time-change information. If you do not know the system's time zone or time zone abbreviation, see Table 3-2 in this book, and the world time zone map in the appendix of the DECnet-Plus DECdts Management guide.

The following example shows the TZR syntax and describes the TZR fields; you can also display similar information by typing a question mark (?) after you choose Option 3 from the Timezone Options menu.

         Timezone Options:

        [0]     Exit Timezone Configuration

        [1]     Choose a timezone using menus
        [2]     Use Universal Coordinated Time (UTC)
        [3]     Type in your own timezone rule

* Enter an option number                                 [1] :3

STDoffset[DSToffset,start[/time],end[/time]]

As an example of a typical TZR, if the rule has the value EST5EDT4,M4.1.0,M10.5.0, it describes the rule for the eastern United States, which became effective in 1987. EST is the designation for Eastern Standard Time, which is 5 hours behind GMT. EDT is the designation for Eastern Daylight-Saving Time, which is 4 hours behind GMT. EDT starts on the first Sunday in April and ends on the last Sunday in October. In both cases, because the time is not specified, the change to and from EDT occurs at the default time of 2:00 a.m.

Since the TZR format is complex, you may want to refer to Table 3-2 to copy the rule for your locale onto the command line, and then edit the rule as desired.