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Year 2000 FAQ
2000 FAQ
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(The following is a Draft document, prepared by Pam Hystad,, for the newsgroup. She maintains her copy at

Phystad's Unofficial Year 2000 FAQ
last updated 1998-04-26)
Pam Hystad, with contributions and suggestions from John Stockton, Flint Cowden, Harlan Smith, and others

This FAQ provides brief introductory answers to common questions regarding Year 2000 problems. It is a general starting point for further research into specific areas of concern. The material presented here will be updated as new information becomes available, and is as timely and accurate as is possible at this time. This document may be copied, in its entirety, for non-commercial or personal use; all rights are reserved by Pamela Hystad, 1998.


The most common misconception about Y2k is that it is a single problem, when in fact the Year 2000 date roll-over will cause a variety of problems. Because all of these errors have the same root cause, and because the remediation processes for many of the defects are similar, many people refer to all date roll-over problems as a single issue. Unfortunately, this perspective has created a commonly-held belief that the "problem" is trivial although widespread, and that a single solution is possible. It must be clarified that the "problems" are both complex and widespread, and that each problem area requires specific and individual solutions. It has been common practice for many years to write dates in abbreviated forms, such as: Mar 3, 98 3 Mar 98 3-3-98 98-03-03 to list just a few of the possibilties. People are generally able to interpret the various abbreviations correctly, and in 2000 will assume, usually correctly, that 3-3-00 is an abbreviation for March third of 2000. Computers, however, are unable to make assumptions. Computer hardware and software must be explicitly directed to perform correct interpretations of the data to be processed. When using only dates from 1900 to 1999, no-one can tell by looking at a screen or a printout whether the computer has Year-2000 compliant software instructions or not.


Most often, computers aren't instructed that "98" is an abbreviation for "1998". Some software instructs the computer that "99" is the highest possible value, to be followed by a return to "00". Some software instructs the computer that 99 is a number, that should be followed by 100. Some software doesn't provide any explicit instruction to the computer about what comes after "99". In some cases, software does command the computer to treat "98" as an abbreviation of "1998". Usually this instruction is performed by inserting the characters "19" in front of the "98". Other types of software tell the computer to add 1900 + 98. There are cases when the addition method will work as well in 2000 as it does now, *IF* the software tells the computer that 99 is a number, followed by 100. In these instances, adding the number 1900 to the number 100 will correctly produce the number, 2000. In many cases, though, the software instructions to the computer will result in an incorrect year of "00", or "1900", or "19100", or will fail to produce any answer at all. Sorts, comparisons, and calculations performed with incorrect year values will result in a variety of unexpected consequences. Depending on the type of software and hardware, these failures could result in garbled reports or they could cause computers to crash.


2000 is a Leap Year and there will be a February 29th, as decreed in about 45 BC, and not altered by calendar changes instituted by the Papal Bull of 1582 and the Calendar Act of 1752. Some software doesn't recognize 2000 as a leap year, and could cause a variety of problems. There are many web-sites which document the rules for calculating leap years, including and


A wide variety of computers are affected by Year 2000 problems, ranging from personal computers for home use to mainframes that run huge corporations, and everything in between. Workstations, client/server systems, networking hardware, processors embedded in machinery, the globally interconnected "system of systems" - none of these are immune to Y2k problems. Hardware, "firmware", operating system software, and applications can all be incapable of handling the Year 2000. Simply upgrading hardware doesn't cure problem applications running on that hardware; and compliant software can't run if the hardware crashes. Any activity performed by any type of computer involving dates after 1999 is at risk, such as software appplications that perform forward planning, financial calculations, processing of taxes, wages, benefits, scheduling, sell-by and expiry dates, school and medical records, retail transactions, reservation systems, transportation, communications -- there is no aspect of our lives that is untouched by computers. In addition, almost all food processing, manufacturing, power generation and transmission, water and waste treatment, and all the conveniences of modern life are conducted by computerized automation. The software and hardware that run electric power plants are as susceptible to Year 2000 problems as the utility company's metering and billing systems.


Date Expansion
The safest solution is to use full four-digit years rather than abbreviations in all dates. Most data entry procedures can be written with instructions for correctly interpreting two-digit year entry, while displaying, storing, and outputting dates with all four digits, and can allow the user to enter four digits if required. Date expansion is unambiguous and will work correctly until 9999, if the hardware and operating systems allow. Date expansion has the disadvantage of requiring changes to the storage space allotted for data; conversion of all existing date data; modification of screens, reports, and other outputs; changes in the software code to handle dates correctly; and the possibility that data-exchange partners may not be able to accept dates in expanded format.

Date Windowing Two-digit year values can be windowed, by assuming that the year must fall within a 100-year range. This method is essentially how abbreviated dates work right now -- the 100-year period is assumed to be from 1900 to 1999, inclusive. If the 100-year range assumption is from 1950 to 2049, and correct instructions are written in the software, the software will perform date processing correctly until 2050. The date window can be set to any 100-year period, or can be interpreted according to the current year (e.g. from 10 years before this year to 89 years after this year). Date windowing requires no changes to data storage, no conversion of old data, and no changes to screens or reports. Date windowing has a number of disadvantages, however. The code to perform the interpretation of dates must be written very carefully, keeping in mind the varying requirements of all of the applications which may use or interact with the dates. Within a single application, an employee birth date may require a window range entirely in the past, while a forecasting function will require a range entirely in the future. All users of the application, and any other application that may share the data, must be cognizant of the assumptions made in every circumstance. At some point most windowing techniques will require further modifications to continue to function. Windowing is inherently ambiguous, and should not be used in applications requiring the exchange of data across systems.

Date Setback There are two types of date setback techniques, one requiring the manipulation of data, and the other involving the system clock itself. The year data can be set back by 28 years (or 56; the calendar repeats itself every 28 years), making "98" appear to be "70" (or "42"). This approach is by far the riskiest, as it involves changes to both code and data; requires alteration of existing date values; and requires manipulation of date values at input to subtract the setback, and at output to restore the amount of the setback. Setting the computer's system clock back by 28 (or 56) years is sometimes an acceptable temporary remedy, for a stand-alone device that has no inputs or outputs from other systems, and if the clock permits a system date of "71" or earlier. Caveat: a company known as Turn Of the Century Solution (TOCS) has received a patent from the U.S. Patent Office regarding a specific type of date setback procedure. The patent description mentions the prior existence of a 28-year date setback technique, so it is unclear what specific methods or procedures have actually been patented.


It isn't possible to predict right now (April 1998) how many computer systems won't get fixed in time, or how badly the failed systems will affect our lives. Nobody really knows whether most people will muddle through somehow, or if civilization will collapse. There are likely to be wide variations in the quantity and the quality of remediation efforts; and geographical differences in the impact of failed computer systems on society. Many people tend to be myopic in their understanding of the extent to which "first-world" technology relies on computers. To date, an estimated 25 billion or so processors have been sold. This is 3-4 processors for every person alive on Earth. On average, many thousands of lines of code have been written per processor. The amount of communication between processors is beyond estimating. All of this has the potential to lead to chain-reactions of failures that are stranger than any fiction. There is a very common tendency for us to say, "I don't know what all might happen, therefore nothing much (or a huge amount) will happen." In truth, the future cannot be predicted even in broad terms. The social consequences of possible widespread computer failures are beyond the scope of this FAQ.


Date Rollover
On many PCs, the clock will go from 1999-12-31 to 1980-01-04. On some PCs, it may look like the clock rolled over correctly, but after you turn it off and back on, the date will be wrong. Most computers will remember the correct date after being manually set, although some older PCs can't be forced into 2000 no matter what you do. DON'T set your PC system date ahead without first taking safety precautions to protect your PC, software, and data.

Leap Year
2000 is a Leap Year and there will be a February 29th, so there will also be 366 days in 2000. Some software doesn't recognize these days, and could cause a variety of problems; incorrect date roll-over on 2000-02-29, 2000-03-01, 2000-12-31, and 2001-01-01; and day-of-week errors after February of 2000.

Inaccurate Time-keeping
A small number of PCs are unable to maintain the correct date and time consistently after 2000. A test to identify this defect, known as the Crouch-Echlin Effect, and a possible software remedy are being tested at this time. This FAQ will be updated as more information becomes available.

Peripheral Devices
There are no known Year 2000 problems with printers, modems, scanners, or other devices commonly connected to PCs. In some cases driver software may have to be updated. Vendors generally provide information for specific models.


Setting the system date ahead for testing may have adverse consequences; at worst, the PC may crash and become unbootable. Licenced software and passwords may expire; forward-dated records may be generated or "too-old" records deleted. Processing centres should test on isolated systems. However, it is usually safe to test a stand-alone PC by booting to DOS from a clean system (bootable) floppy disk, and running no applications -- after making and testing a backup of the hard drive. There are a number of step-by-step guides to safe testing procedures: (the safest and most comprehensive guide) (a good step-by-step test procedure for PCs)

There are a number of software test tools to automate the process, and some that promise to fix the incorrect dates automatically. Please see the list of URLs below.

Start getting accustomed to using the "YYYY-MM-DD" date format now. For a helpful discussion of the ISO-8601 date format recommendations, see In Windows, set the default date format to year/month/day order, with 4-digit year and leading zeros in month and day. Most current Windows software applications use this default setting, so many applications will use this format as soon as the Windows default is set correctly. However, all applications should still be checked, and the date default set if necessary. In addition to familiarizing yourself with this date format, applications that truncate date fields or use date values incorrectly will be easier to identify. See Chris Anderson's site for excellent instructions, notably: Ask vendors about Y2k compliance before buying new software or upgrades. Many of the sites listed below provide compliance information, known problems, or safe testing procedures for some common software packages.


Yes. The Global Positioning System (GPS) week number will roll over from week 1023 to week 0 in August 1999. The clock on some Macintosh computers cannot be set after 2019. Asteroid 1997 XF11 will miss Earth in 2028. UNIX has an overflow problem in 2038. For a list of critical dates, see


Personal Preparation
Personal preparation can be as simple as stocking up on candles, food staples, potable water, and batteries; or as all-encompassing as moving to a rural location and becoming as self-sufficient as possible. There are as many opinions on how to ensure personal safety as there are online resources for every level of preparation. Several of the sites listed below are good starting places for individual planning efforts. Obtaining paper copies of important records; writing to service and utility providers requesting information on their compliance and contingency plans; making sure to have some cash on hand, extra prescription drugs, and a full fuel tank in the car -- these are some cheap, easy, very basic precautions everyone should take.

Raising Awareness
Write letters of enquiry to government representatives and agencies, service and utility providers, all the businesses and organizations you rely on to maintain your lifestyle. Don't forget to ask questions of your employer! Several of the URLs listed below include sample letter templates that you can use. Talk to your family and friends; they might think you're crazy, or they might invite you to visit their rural farm over Christmas and New Year's of 1999-2000!


Further reading is essential. Many articles, of all sorts, are available. The following is just a small sample of many helpful sites. (URLs verified on 1999-01-02)

United States Chemical Safety and Hazard Investigation Board

Rick Cowles

Chris Anderson and

Tony Toews

Dave Eastabrook

Mike Echlin

Randall Bart

Scott Olmsted

John Stockton (Year 2000 and Miscellaneous Information Sections)
Westergaard Year 2000

Cassandra Project

Natasha's Site, and Web-Ring for Y2k sites and

Greenwich 2000

Computer Professionals for Social Responsibility

AIAG (Automotive Industry Action Group; embedded systems)
Institute of Electrical Engineers

Electric Power Research Institute

Ed Yourdon

Ed Yardeni (Deutsche Morgan Grenfell)

Year 2000 Information Network

Roleigh Martin

Mitre Corp.

Peter DeJager

Gary Eubanks

The Disaster Center

Gary North

(Consulting firm, helpful info on their pages)

Wilson White Group, New Zealand

Computer Information Centre

International Banking

Canadian Solutions Vendor


GOV stuff -- some with large databases of vendor compliance statements. Note: some of these sites have areas accessible only to .gov domain users. ----------------------------------------------------------------------

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Revised 1999-01-06

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