Copyright: Copyright © 1995, UK, John M.Howells
Citation: Copyright © 1995, UK, John M.Howells


Contents
World Time Zones Display © 1995, John M.Howells

Main Window

Time Zone Select

Time Zone Detail

Time Zone Detail (No DST)

Please Note: The program displays the Time Zone Information from the Windows NT Registry on the assumption that it is applicable to all the years from 1901 to 2099, an assumption that is unlikely ever to be correct. The information for any particular year in a Time Zone should therefore not be relied upon, and corroboration should be sought.


Time Zone Select

This Dialog Box allows the user to select which Time Zone is displayed for an entry in the main display. It is started by one of the buttons in the column on the left of the main display.

The Dialog Box shows a scrollable list of all the Time Zones known to the Windows NT Registry.

Time Zone currently selected.

When the entry in the main window has a Time Zone selected the Dialog Box opens with the associated selection highlighted.

The Cancel button closes the Dialog Box without changing the current selection in the main window.

The Clear button closes the Dialog Box and removes any display from the associated entry in the main window, except for the first entry, for which the Clear button displays the information for the Local Time Zone.

The OK button closes the Dialog Box and displays the data in the associated entry in the main window for whichever Time Zone is then highlighted.

The user can also highlight a Time Zone name and double-click on it to close the Dialog Box and display the data for that Time Zone in the associated entry in the main window.

No Time Zone currently selected.

When the associated entry in the main window has no Time Zone selected the Dialog Box opens with no selection highlighted

The Cancel and Clear buttons close the Dialog Box without selecting any Time Zone for display in the associated entry in the main window.

If a Time Zone is selected, by clicking on it, the OK button closes the Dialog Box and displays the data for selected Time Zone in the associated entry in the main window.

The user can also highlight a Time Zone name and double-click on it to close the Dialog Box and display the data for that Time Zone in the associated entry in the main window.

Storage of User selections.

The selections chosen with the OK or Clear buttons will be stored in the Windows NT Registry separately for each user, and the last set of selections for the current user will be restored when the program next starts.

Time Changes.

If the time changes while this Dialog Box is displayed, or a new Time Zone is selected for the system from the Control Panel, the Dialog Box will be cancelled with no change to the selected entry.


Time Zone Detail

This window shows the detail of a Time Zone in which Daylight Saving Time (DST) applies.

It should be noted that the program displays the Time Zone Information from the Windows NT Registry on the assumption that it is applicable to all the years from 1901 to 2099, and that the Gregorian calendar applies to all those years, both assumptions that are unlikely ever to be correct. The information for any particular year in a Time Zone should therefore not be relied upon, and corroboration should be sought.

The display starts with the current year for the system. The Now! button returns the display to the current year, while the << and >> buttons select previous (<<) or subsequent (>>) years to be displayed, allowing the display to be stepped back to 1901 or forward to 2099.

For each year the display shows the date and time of the changes to and from Daylight Saving Time (DST), and the name used for the two time periods. The display also shows the time in the Time Zone after each time change.

The first change shown will be the date of the earlier change in the year. This will usually be the change to DST in the Northern Hemisphere and to Standard Time in the Southern hemisphere. The second change shown will be for the other time period, usually to Standard Time in the Northern hemisphere and to DST in the Southern hemisphere.

Dates for a Time Zone change are normally stored in the Windows NT Registry in 'day-in-month' format. This display shows that format and also the true date after conversion to a normal calendar date for the year concerned.

The display also shows the data stored in the Windows NT Registry that usually shows the offset (bias) from GMT (UTC) and the places that use the Time Zone.

This Dialog Box will be cancelled if the time changes, or a new Time Zone is selected for the system from the Control Panel, while this Dialog Box is displayed.


Time Zone Detail (No DST)

This display is used for those Time Zones that do not use Daylight Saving Time (DST). It shows only the data stored in the Windows NT Registry that usually shows the offset (bias) from GMT (UTC) and the places that use the Time Zone.

This Dialog Box will be cancelled if the time changes while it is displayed, or if a new Time Zone is selected for the system from the Control Panel.


Main Window

This is the main display for the program.

Note, that the program relies on the Time Zone Information in the Windows NT Registry to determine the data for any Time Zone displayed, so that an incorrectly reported change is as likely to be due to errors in that data as anything within the immediate purview of this program.

This shows the main window with a Time Zone selected for each entry.

Time Zone Display

The display for the entry across each row shows the name in the Windows NT Registry of the Standard Time in the selected Time Zone, together with the current time and date in that Time Zone.

By default the first entry will display the information for the Local Time Zone if no other Time Zone is selected.

For a Time Zone that uses Daylight Saving Time (DST) the display for the entry also shows whether the Time Zone is currently using DST, and the time and date, in that Time Zone, of the next change to or from DST. This will be from Standard Time to DST if Standard Time is currently in operation (No in the DST window), or from DST to Standard Time if DST is currently in operation (Yes in the DST window).

For a Time Zone that does not use DST the items associated with DST (those other than the Time Zone name and the current date and time) are blanked out.

Time and Date display Format

The times and dates always use the default for the language selected for the system in the international setting of the Control Panel, except that the time always uses a 24 hour clock. If the language is changed while the program is running the display will continue to show the original format until the program is stopped and restarted.

Save Position

When the 'Save Position' box is not checked the display will startup in the centre of the screen.

When the 'Save Position' box is checked the program will save its last on screen position when closing (even if being closed when iconized), and will restore to that position next time it starts. However, if that position would result in the top left corner of the display being within 100 pixels of the right hand side or the bottom of the screen the display will be centred. The saved position will be stored in the Windows NT Registry separately for each user.

Initial Display

This shows the main window when the program is started for the first time (or after all the user selected entries have been cleared), with the first entry displaying the Time Zone Information for the Local Time Zone and all the other entries empty.

Time Zone Selection

The buttons down the left of the display open a Dialog Box that allows the user to select which Time Zone should be displayed in that entry (see Time Zone Select). The user can select from any Time Zone entry stored under the Time Zones key in the Windows NT Registry.

The selection in each entry will be stored in the Windows NT Registry separately for each user, and the last set of selections for the current user will be restored when the program next starts, unless a previously selected Time Zone has been deleted, in which case the associated entry will be blank.

Time Zone Detail

The buttons down the right of the display allow the user to select more detail about the possible time and date of changes to and from Daylight Saving Time (DST), depending on whether or not DST applies in a Time Zone (see Time Zone Detail for those Time Zones which use DST and Time Zone Detail (No DST) for those Time Zones which do not).

The Detail button is greyed out for each entry with no Time Zone selected.

Time Changes

If the time changes, or a new Time Zone is selected for the system from the Control Panel, while this Dialog Box is displayed the Time Zone Information will be updated, and the first entry will be changed to reflect the Local Time Zone in use.


Popup Windows NT Registry
Windows NT Registry

The Database that holds data defining the configuration of

the system, its users, and their preferences. This program

stores the name of each Time Zone selected by each user

separately for that user.


Popup Time Zone
Time Zone

A range of longitudes where a common Standard Time is used,

suggested by Charles F.Dowd of Saratoga Springs, New York, in

1869, and first adopted by the U.S. and Canadian railroads in 1883.


Popup day-in-month
Day-in-Month format

The usual format for the definition of the dates in the

Time Zone Information in the Windows NT Registry

for the transition to and from Daylight Saving Time,

in which a date is stored as the M'th occurrence in

the N'th month of a given day of the week. The 5th

occurrence is used to indicate the last in the month..


Popup Daylight Saving Time
Daylight Saving Time (DST)

The achieving of more evening daylight, usually in the

Summer, by setting the time ahead of Standard Time,

usually by one hour, though at least in the Netherlands

Daylight Saving Time was once set two hours ahead.


Popup Time Zone Information
Time Zone Information

Data in the Windows NT Registry holding the names of the

Time Zones known to the system, the bias (offset) of each

Time Zone with respect to UTC, and If Daylight Saving Time

is used it contains the date and time for the start and end

of Daylight Saving and the name for Daylight Saving Time.


Popup Local Time Zone
Local Time Zone

The Time Zone currently selected by the Date/Time applet

in the Control Panel to define the computer's Time and Date.


Popup UTC
UTC

Universal Coordinated Time (Universel Temps Coordonné

in the original French) or Universal Time Convention, also

previously known as GMT. The international definition for

the measurement of time, that defines a standard against

which all clocks can be measured.


Popup Gregorian calendar
Gregorian Calendar

Originally authorised by the Council of Trent (at Trento Italy) under

Pope Paul III in 1545 and introduced by Pope Gregory XIII in 1582,

which defines only a century that is divisible by 400 as a leap year.

It corrects a small error in the Julian Calendar due to the difference

in the average year of 365.25 days assumed by that calendar and

the true figure of 365.242199 days, which resulted in an annual error

of 11 minutes 14 seconds, or seven days in 1000 years, or 11 days

by the time the Gregorian Calendar was first introduced. However,

the introduction was only gradual, being introduced to France, Italy,

Luxembourg, Portugal and Spain in 1582, to Belgium and to most of

the German Roman Catholic states and parts of the Netherlands by

1584, Switzerland started in 1583 but did not finish until 1812, it was

introduced to Denmark and most of the German Protestant states

in 1699 and 1700, to the United Kingdom in 1752 (when Thursday

the 14th September followed Wednesday the 2nd September), to

Japan in 1873, to the Soviet Union in 1918, and to Greece in 1923.


Popup Julian Calendar
Julian Calendar

Introduced to replace the Roman Republican calendar by Julius Caesar

in 46 B.C (according to modern reckoning), in which each normal year

is made up of 365 days, every fourth year having an extra day between

February 23rd and 24th, giving 366 days. However, the small inaccuracy

in the annual average of 365.25 days meant that an 11 day error had

accumulated by the time the Gregorian Calendar was introduced in 1582.


Invisible Comment
95-01-12	Corrected some upper cases of time to Time.

95-01-13	Added page for Easter and associated triggers.

95-01-17	Changed contents page title and added copyright

95-01-21	Added missing 'Main Window' to Search strings