Entering a Date

You can enter the date in almost any format you like, and when you leave the date box, the date will be converted into Solar Fire’s standard format. If you enter an impossible date such as February 30 or a month number greater than 12, or use a format that the program does not understand, then you will get an error message and be given a chance to try again.

There is also a group of three spin buttons to the right of the date entry box. These buttons allow you increment the individual parts of the date upwards or downwards without having to retype the entire date. For example, the rightmost spin button allows you to change the year number up or down by one year at a time.

Following are some examples of valid dates, and the manner in which they are displayed by the program.

The display format that Solar Fire uses is based on the date order settings within Windows, which may be set by using the Regional Settings icon on the Windows Control Panel.

Description of Format

You must enter a day, month and year, separated by any of the following characters: blank( ); slash(/); period(.); colon(:); semi-colon(;) or comma(,). If you use a month name or abbreviation instead of a month number, then you do not need to use any separators. You may also enter just a day number, in which case the last entered month and year are assumed, or just a day and month in which case the last entered year is assumed. You may also enter just a 4 digit year number, in which the day and month are automatically set as 1st January.

•A day number (e.g. 1, 2, 3, ..., 31). You may also use any of the following suffixes: "st", "nd", "rd" or "th".

•A month name, abbreviation or number (e.g. Jan, Feb, Mar, ..., Dec, or 1, 2, 3, ..., 12). These must be English month names, but may be in upper, lower or mixed case. Abbreviations must contain at least the first three letters of the month name. If you use a month name or abbreviation, then it does not matter whether you put the day or the month first. However, if you use a month number, then you must ensure that you enter the date in whatever order has been set in Windows. See Selecting a Date Format for instructions on settings the Windows date order.

•A year number (e.g. 57, 1957, 2005, -6). You may also use any of the following epoch indicators: “AD”, “A.D.”, “BC”, “B.C.”, “CE”, “C.E.”, “BCE”, “B.C.E”. If you only enter two digits, then the year is assumed to be within the time window specified in the Preference settings. To enter dates in the 1st century, you must use a 00 prefix (e.g. 0059 for year 59).

Optionally there may also be any of the following items:

•A calendar style indicator (i.e. OS, O.S., NS, N.S.)

The epoch is assumed to be AD unless BC or BCE has been entered, or if the year is negative. If the year is negative, then Solar Fire will automatically convert the year into a BC year, and remove the minus sign. (Note that there is a difference of 1 year between BC years and negative (astronomical) years e.g. the year -6 is converted into 7 BC. This is due to the absence of a year 0 in the BC format.)

Modern and Old Calendars

Unless you specify otherwise (by entering an OS or NS suffix), Solar Fire assumes that the dates that you enter...

•on or before 14th October 1582 are in the old style (Julian) calendar.

•on or after 15th October 1582 are in the new style (Gregorian) calendar.

The Gregorian calendar was not adopted everywhere at the same time. Sometimes dates after 15th October 1582 are given in terms of the old style calendar (often followed by the initials O.S.). Also, some sources convert pre 1582 dates to new style dates (often followed by the initials N.S.).

If you wish to enter a date on or after the 15th October 1582 which is expressed as an old style date, then add the suffix “OS” or “O.S.” to the entered date (e.g. 17 Dec 1723 OS).

If you wish to enter a date before the 15th October 1582 which is expressed as a new style date, then add the suffix “NS” or “N.S.” to the entered date (e.g. 7 Jan 1503 NS).

The way in which these dates are displayed in Solar Fire depends on user-modifiable preferences. You can determine whether or not Solar Fire will automatically convert any entered dates into the default calendar for that date, or alternatively whether any dates that you enter with an OS or NS suffix will always be displayed exactly as they were entered. Additionally, you can specify a range of years between which the OS or NS indicator is displayed with all dates. See Changing Preferences for more details.

The following table shows the adjustment that Solar Fire makes in order to convert from old style to new style dates:-