OfficePower and Year 2000

Dates - 2 or 4 digit years?

The general rules for storing dates within OfficePower (for example, within a field of a datafile record) are:

1. OfficePower/Xtra stores dates internally with full year values, whether they are displayed with 2 or 4 digits for the year.
2. Where a date is ENTERED using a one or two digit year, OfficePower infers the century using a pivot date of 1st January 1961 - thus 31/12/60 is taken to mean 31st December 2060, whilst 01/01/61 is 1st January 1961.
3. Where a date is entered with 3 or 4 (significant) digits for the year, this is taken to be the complete year.
4. Leading zeroes are ignored when entering years - so 1/1/1, 1/1/01, 1/1/001, 1/1/0001 are all taken to mean 1st January 2001.

However, UNIX itself cannot handle dates outside the range 1st January 1970 to 31st December 2035 (or 19th January 2038 in some versions of UNIX). As a consequence of this:

1. Where OfficePower stores dates which are compared with the current date stored in UNIX, such as in Calendar, it will not accept dates outside the range 1st January 1970 to 31st December 2035.
2. In other cases, such as within UDAPs, although OfficePower can accept dates outside the range supported by UNIX, OfficePower cannot calculate the correct day of the week for any date outside this range; in such circumstances, it will display ???? in place of the day name (if the date is displayed using a picture which includes the name of the day).

In Calendar, Mail and other parts of OfficePower affected by A above, the inference rule becomes:

5. Dates are entered and displayed with two digits for the year. Values in the range 70 to 99 denote 1970 to 1999. Values in the range 00 to 35 denote 2000 to 2035. Values in the range 36 to 69 are regarded as invalid.

OfficePower 20/20 (spreadsheet) has different rules for handling dates.

1. If 20/20 is set to display two digit years, dates entered as a label with only two digits for the year will be taken to mean 1901 to 1999.
2. Dates entered as a label with four digits for the year, or dates entered as values can take the full range supported (see below).
3. If 20/20 is set to display two digit years, dates entered as above will be displayed with only the last two digits of the year - such dates would then be interpreted as in the year range 1901-1999 if used in subsequent calculations, e.g. the DAYS() function.
4. To use dates after 31st December 1999, use /OPTION DISPLAY DATE to select a date format with four digit years. Dates entered as a label must then be entered with four digit years, and all dates will be displayed with four digit years.
5. The range of dates supported (for entry as a numeric value, or entry as a label with four digit years) is 1st January 1901 to 31st December 2100. (However, this range is adjusted slightly if you've used the /OPTION VERSION DATE command to reset "Day 1".)

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