Microsoft Year 2000 Readiness Disclosure & Resource Center

Product Summary

Product: Excel 5.0 Version: Category: Compliant# Operating System: 16-Bit Win Language: Chinese - Traditional Release Date: 31 Aug 1994 Operational Range: 01 Jan 1900 - 31 Dec 2078 Prerequisites: None Product Dependencies: Microsoft Windows 3.1 or above or Microsoft Windows NT 3.1 or above Clock Dependencies: Operating system clock Last Updated: 18 May 1999

Product Details

How the product handles dates: Storage. Microsoft Excel stores dates as numeric values, with day #1 being 1900/01/01. Excel 5 recognizes 01-JAN-1900 through 31-DEC-2078 as valid dates. 01/01/2000 is stored as value 36526, since it is the 36526th day in the century. Formatting. When Microsoft Excel formats a date, it uses one of several default formats. The most common is the system short date. If the system short date is a YY format (YY refers to a 2-digit year entry), then even when the user types a YYYY date (a 4-digit year entry), it will by default display in a YYYY format. The date format is customizable. For customers requiring the highest level of predictability concerning their date data, Microsoft recommends changing the system short date to a YYYY format Parsing on date entry. If a user enters a date in a "yy-M-d" format, less than 20 is interpreted as 20XX, and equal to or greater than 20 is 19XX. For example, Excel 5 will recognize, "15-01-01" as January 1, 2015, but will recognize "25-01-01" as January 1, 1925. To avoid any possible confusion, however, users can display dates in a YYYY format so the century is clearly shown. If a user enters a date in a "yy/mm/dd" format, it will be interpreted as a Republic of China era date. For instance, "1/2/3" will parse to 03 FEB 1912. To avoid ambiguity, enter dates in a YYYY/MM/DD format so the date can be clearly understood. On a default Chinese Traditional system, if a user enters a 21st century date in a "mm/dd/yy" format, some cases will be interpreted as a "yy/mm/dd" format. To avoid ambiguity, enter dates in a YYYY/MM/DD format so the date can be clearly understood. Leap Year. Microsoft Excel treats 1900 as a leap year for backward compatibility with other products such as Lotus 1-2-3. (See Knowledge Base (KB) article Q181370 for more information.) Two-digit shortcut handling: See discussion above. Conversion of 2-digit shortcut dates assumes a date window of 1920 through 2019. (See Knowledge Base article Q164406 for more information.) Common date usage errors: If a date is pasted from one application to another using only the last two digits of the year, Microsoft Excel 5 might parse the date differently than the originating application calculated it. Example: In a non-Excel application, you have the date January 1, 1915. You copy the date, but your system settings are "M/d/yy", and all that is copied is the text "1/1/15". When you paste "1/1/15" into Microsoft Excel, it will parse the date to January 1, 1926 (R.O.C. era 15, January 1). This can also occur when one application is using a "M/d/yy" format while another application is using a "d/M/yy" format. This also applies to importing dates from text files. The DATE() function is not designed to take 2-digit year shortcuts, since it receives numeric parameters. The DATE() function calculates a number less than 1900 as an offset from 1900. So, if you were to enter a formula such as =DATE(15,1,1), the resulting date would be January 1, 1915, not 2015. Recording date entry in a macro records the year according to the system short date format, which results in parsing a 2-digit year in playback. (See Knowledge Base article Q182766 for more information.) Using a format such as "Dec 98" will not be interpreted at the year 2001. This is because 98 is too large to be the day of month, so Microsoft Excel assumes it is a year. However, Excel 5 assumes "Dec 01" refers to December 1 of the current year. (See Knowledge Base article Q180952 for more information.) Microsoft Excel 5 handles serial dates, the most common usage of dates, properly. Due to the ambiguous nature of text dates, in general they do have some potential for error. Use serial dates whenever possible and take great care when transferring text dates. Change the default system short date format to include a 4-digit year. Get in the habit of using 4-digit year formats for dates in Excel. Such a practice will make the date visible if a user mistakenly enters a date in the wrong century. When dates must be transferred between applications, ideally they should be transferred as serial dates. They should not be transferred as an ambiguous text format that doesnÆt specify the century and causes confusion between month and day-of-month. For example, the text "25/2/1" could be interpreted as Feb. 1, 1925, Jan. 2, 1925, Feb. 1, 2025, Jan. 2, 2025 or Feb. 1, 1936 (R.O.C. era 25, Feb. 1). Defined names store references as text strings. Since they do not store dates as serial values, they are susceptible to century issues when a 2-digit format is used for the year. Using defined names in this way is also problematic because users who use a date format with an order other than M-d-y will experience misinterpretations. Recommended usage is to define the name referring to a cell containing a serial date, which will avoid both of the above-mentioned potential problems.   Testing guidelines and recommendations: In general, avoid testing in a production environment or with non-duplicated production files because one cannot predict side effects with other products. Interoperability testing with other Microsoft Office products can be conducted safely. The following areas should be examined to verify dates are being properly used. The table below can be used to guide testing of Microsoft Excel within your organization. Sub-system Component File Various File Formats Avoid storing 2-digit dates in text file formats such as TXT, DIF, CSV, and PRN. The default column width with default fonts may truncate characters with date formats that have 8 digits and two separators. To resolve, increase the column width, or change the font to a fixed-width typeface such as Courier New. Data Import from: text, Databases, External data sources Sort Data imported from databases and other external sources is often imported as text. In general, importing 2-digit dates will be parsed as R.O.C. era dates. They will parse as Gregorian dates with a 2019/1920 cutoff when the separator used for date entry is different from system setting (Ex: Date entry is 05-01-01 and date separator of system setting is "/" in the Control Panel û Regional Settings). This is different from later versions of Excel, so use 4-digit dates to prevent confusion. Basic Use Functions Date Entry Natural Language Functions Functions referring to text dates will parse according to the 2019/1920 cutoff rule. In general, date entries will be parsed as R.O.C. era dates first. They will be parsed as Gregorian dates with a 2019/1920 cutoff when the separator used for date entry is different from system setting (Ex: Date entry is 05-01-01 and date separator of system setting is "/" in the Control Panel-Regional Settings). Visual Data Charts Since chart labels are normally used for display, and not for calculation, this shouldn't pose much of an issue. Visual Basic/ Visual Basic for applications Transfer between VB/VBA and cells Internally, Visual Basic for Applications treats dates as serial values, exactly like Excel. However, since VBA uses the "M/d/yy" format, you should avoid transferring the date text through VBA, since it could parse to the wrong century. This will also help avoid issues with international users who have a system short date format with an order other than M-d-y. Additional Testing Instructions Microsoft understands that for various reasons customers may be required to conduct their own year 2000 certification testing. Microsoft provides the tests below to aid customers in conducting their own year 2000 certification of Microsoft Excel 5. Users who work with dates in Microsoft Excel 5 will benefit from changing the system short date format to one that uses a 4-digit year, (i.e. "yyyy/MM/dd"). This change will allow the user to clearly see the century of a date. Conducting the below tests is only worthwhile if 4-digit years are used. If you decide not to set your system short date format to include a 4-digit year, you can format each cell individually by selecting Format/Cells/Number/Custom, and entering a 4-digit year format. To change the system short date format, press the Start button, then select Settings, Control Panel, Regional Settings, select the Date page, then change the Short Date Style to a format that includes a 4-digit year by replacing the "yy" portion with "yyyy". Verify that Microsoft Excel transitions smoothly into the year 2000: Warning! Before conducting this test, make sure you do not have any software containing a license that expires by the year 2000. This is especially common with beta copies of software programs. If a program determines that its license has expired it is possible the program will no longer boot, even after resetting the system clock. Changing a system clock on a network can affect other computers connected to the network so it is highly recommended that you isolate the computer from other systems before changing the system clock to conduct the following test. Set the system clock to 11:59 p.m. December 31, 1999. Start Microsoft Excel 5. In cell A1 (cell R1C1 if in R1C1 mode), enter =NOW(). After one minute, press {F9} to recalculate the formula you entered in A1. Note that the time and date shown will be in the year 2000, and nothing unusual has happened to Excel 5. Remember to reset your system clock to the correct time and date after conducting this test. Verify that Excel 5 recognizes the year 2000 as a leap year: Start Microsoft Excel. In cell A1 (cell R1C1 if in R1C1 mode), enter "=DATE(2000,2,28)+1". Note that the resulting date is February 29, indicating that Excel 5 correctly recognizes that 2000 is a leap year. Note: The year 1900 is not a leap year. However, in your testing you may notice that Microsoft Excel 5 treats 1900 as a leap year. This algorithm was adopted to maintain compatibility with dates in Lotus 1-2-3, and is by design. The calculation for leap years used by the Gregorian calendar is as follows. If a year is evenly divisible by four, it is a leap year, unless the year is evenly divisible by 100. If a year is evenly divisible by 100, it is not a leap year, unless it is also evenly divisible by 400. (See KB article Q181370 for more information.)

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ANY MICROSOFT YEAR 2000 STATEMENTS MADE TO YOU IN THE COURSE OF PROVIDING YEAR 2000 RELATED UPDATES, YEAR 2000 DIAGNOSTIC TOOLS, OR REMEDIATION SERVICES (IF ANY) ARE SUBJECT TO THE YEAR 2000 INFORMATION AND READINESS DISCLOSURE ACT (112 STAT. 2386). IN CASE OF A DISPUTE, THIS ACT MAY REDUCE YOUR LEGAL RIGHTS REGARDING THE USE OF ANY SUCH STATEMENTS, UNLESS OTHERWISE SPECIFIED BY YOUR CONTRACT OR TARIFF.

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