Those benefiting from this site are invited to contribute to some local charity.

Please do not fetch this Web page (or others of mine) by automated subscription; that wastes my resources. Because of this abuse, I may sometimes change the name or offer only critdate.zip.

Copying

I do not permit the wording of this list of dates to be copied on the Net or elsewhere, either in whole or on part, except for "fair comment" extracts; but the dates and the facts are naturally public. By breaching my copyright, you implicitly agree to termination of your account.

I do not permit this Web page to be copied, except in these cases :-
(i) as described in my Merlyn Home Page page,
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(iv) for personal private reference.

I may agree to limited copying within organisations. All copies must be headed with a proper attribution, must cite it as <URL:http://www.merlyn.demon.co.uk/critdate.htm>, and must give the date made.

Citation

Normal Web links to and citations of this page are welcome (there is no need to ask).

Those intending citation in popular print or broadcast media are requested to consult me first about cacheing or mirroring, and about relative links.

Critical Dates

The major criticalities are, sequentially, the August 1999 GPS rollover, the Year 2000 and all its two-digit rollover consequences, the Leapness of 2000 (including Day 366), and the 32-bit UNIX (and C library) Year 2038 problem; and also the various dates relating to introduction of the Euro currency.

There are or have been other critical date lists at Cinderella "Timeline", at Volker Kolberg's site, in Capers Jones's "Dangerous Dates" page, etc., etc. My more general Year 2000 and Date/Time references are now on other pages. Excerpts on Computer Calendar-Clock Problems by Peter G. Neumann (2000) is instructive. Some errors are described in Software Horror Stories by Nachum Dershowitz, with links.

Much of the following was picked up from the comp Y2k, UK Y2k and Risks (Risks Digest) Usenet newsgroups and from a Y2k FAQ, with the aid of the Calendar FAQ; also doncio and other Web pages such as at Mitre.

When I receive E-mail information correcting or extending the list, I will assume permission to quote.

The List of Dates

This is, fundamentally, a list of Critical and Significant Dates, which is not quite the same thing as a list of dates which ought to be used in testing; for example, 2000-02-29 was critical as possibly unexpected, but in testing one should also try 2000-02-28, 2000-02-30, 2000-02-31, 2000-03-00 & 2000-03-01, in order to make sure that the valid dates are consecutive and without overlap (Note 19); likewise for 2000-366. Some of the dates are those resulting from other date failures.

Some are important; some are possibly just amusing - it is up to you to discriminate.

This List is not a prediction of disaster; it is an indication of when error may be prevented by sufficient care.

The Gregorian calendar, with Historical year numbering, is to be assumed where necessary (some dates are UNCHECKED - you MUST verify - they may be a day or two out). However, many of the critical dates would be the same dates (which currently occur thirteen days later) in a consistently Julian environment. Note that, in computing, conventional day-numbers preceding 1900-03-01 and day-counts spanning 1900-02-28 to 1900-03-01 might be a day out, if a day in between those dates was assumed.

The more Critical Dates may have been chosen as trigger dates by virus writers - 2000-01-01, 2000-02-29, 2001.02.29, etc. - and may emulate date errors.

Some dates of non-computer origin are included. Historical dates are mainly limited to those of significance to UK history and culture.

Virus trigger dates are NOT included - use a virus checker such as F-Prot (see PC Links Reference) and others.

2006-08-01 - New Warning

In general, I have mainly considered events relating to counting UP to particular numbers. There are also events relating counting DOWN; and those are less well predicted.

The Dates Themselves

Date Formats

To simplify use of my DoW checker :-
• Julian dates are given as YYYY/MM/DD.
• Only Gregorian AD dates are ISO 8601 hyphen-separated, unless invalid, when dots are used : otherwise, spaces are used.

Timing of Events

Some of these are local date/times; some are GMT/UTC or similar. I use GMT for legal GMT, with date changing at London mean solar midnight; the term UT might be confused with UTC.

It is very important to remember that the local time corresponding to a given GMT depends on the local Time Zone, and on Daylight saving; also that the time in question will be the time that the system is actually set to, not what it should be set to.

For example, a DOS/Windows PC will with high probability be set to local time internally, but a UNIX computer should be on GMT/UTC internally. DOS software translated from UNIX may default to California time settings.

The form a^b is used for "a to the power b" = a^b. The form mEe is used for m×10^e.

N.B. Two aspects of the year before AD 0001 are presented below, as BC 0001 and as ±0000 Astronomical.

To determine CMJD and/or Day-of-Week, see "mjd_date", "bat_date", "nowminus", and "dateprox" in my programs directory; "longcalc", which works in wide-range exact integer seconds, can be used for dates after Y32k; see also Zeller. For a JavaScript calendar, JavaScript Calendars and Clocks.

1 :-

"These are machines built by Apollo Computer, running the DomainOS operating system (DomainOS is Not Unix, BTW). The fail date is 14:59 GMT November 2, 1997. At that time, the highest bit of the 32-bit system clock value will go to '1'. Some functions may treat this a signed integer, and will give erroneous values if they use subtraction to calculate elapsed time."
http://www.mitre.org/research/cots/APOLLO_PROBLEM.html
http://www.mitre.org/tech/y2k/docs/DATES.html
http://www.InterWorks.org/Tech/apollonov2/
Thread "Hp's Computers" in news:comp.software.year-2000, Oct'97.
E-mail 2001-04-19 - these are really Apollo machines, from before the HP takeover in 1998. Good patch info from Jim Rees; 1997-11-02 14:59 is an erroneous 31-bit rollover; the genuine 32-bit one is at 2015-09-05 05:58.

2 :-

This set is largely derived from Randall Bart :- Erroneous date-form is longer than ever before - field overflow is possible - null-terminated strings may lose termination. Date-form occurs when (Year-1900) is printed with %d, %2d or equivalent, and Year>1999; the "19" may be implicit or explicit; leading zero may be truncated. Date strings are here in UK D/M/Y order, or Ordinal Date Y-D. Note 3.

????-??-?? - The day on which "YY" is changed to "YYYY"
2000-01-01 - "01/01/100" - N.B. UNIX tm-year is (Year-1900).
2000-01-01 - "100-001" - (YY overflow & %3d daycount).
2000-01-05 - "Wednesday, 05/01/100"
2000-01-10 - "10/01/100" (format string "%d/%2d/%2d")
2000-01-12 - "Wednesday, 12/01/100"
2000-04-09 - "100-100" (YY overflow & %d daycount)
2000-09-01 - "01 September 19100"
2000-09-06 - "Wednesday, 06 September 19100"
2000-09-10 - "10 September 19100"
2000-09-13 - "Wednesday, 13 September 19100"
2000-09-27 - "Twenty-seventh [of] September 19100"
2000-10-01 - "01/10/100" (format string "%2d/%d/%2d")
2000-10-04 - "Wednesday, 04/10/100"
2000-10-10 - "10/10/100"
2000-10-11 - "Wednesday, 11/10/100"

In languages other than English ...
These may occur in 1999, if the date format has been changed from YY to YYYY.

3 :-

If in conjunction with time as %d:%d:%d, full length is not achieved until mid-morning.

4 :-

And non-UNIX 32-bit or compatible C/C++ libraries, etc., which means that the bug can appear in, for example, DOS programs; I may have found it in ZIP.EXE, from ZIP22X.EXE, from Info-Zip via FTP sites. It's been reported in Microsoft MFC CTime class. It's been seen in control software. It's alleged in Word Perfect 6.1 (for ?). In UNIX, 03:14:08 is GMT/UTC; in DOS/Win3/Win9x, it's local time.

5 :-

Unisys A Series system date, various possible year overflows in 1987, 2003, 2036.

6 :-

Microsoft's help file: "mktime handles dates in any time zone from midnight, January 1, 1970, to midnight, February 5, 2036."

7 :-

In 2000 .. 2009, code using 'printf("Year=%d", yy)' will print 0 .. 9 rather than 00 .. 09; so 'printf("Year=%d%d", cc, yy)' will print 200 .. 209.

8 :-

Code using %2d to write tm_year = Year-1900 to a string, then moving the first two characters to a print field, will in 2000-9 give 10, 2010-9 give 11, ...

9 :-

Moving yyyy mod 100 (as opposed to yyyy - 1900) into a string with %d format will in 200X give an X followed by an unmodified byte.

10 :-

Graham E. Kinns wrote (Jul 98) : SNews has a severe 9th Sep 2001 problem when the decimal representation of time_t rolls from 9 to 10 digits, breaking the fixed format of the .idx files :( I believe the same applies to NewsWin.
Richard Clayton wrote in article <+ypcqNIrBmY4EAt2@turnpike.com> of Thu, 23 Dec 1999 17:48:27 in news:demon.ip.support.pc that the new SNews 1.31 fixes this.

Philip Guenther (mail, Apr 2001) reports that "maildir" mail format usually includes the time_t value in decimal at the start of the filename, and that this is often used for sorting; mis-sorts expected from Sep 9.

11 :-

"Both localtime() & time() are Perl equivalents of the corresponding C functions and use them internally. But what most Perl programmers probably do not know is that time(3c) will return (( time_t )-1) if it fails for any reason, so localtime(-1) will happily return a formatted date string for 'Wednesday December 31, 1969'." Risks Digest 19.88/7.

12 :-

It's suggested that 2000.01.00 may lock Pentiums up irrevocably.

13 :-

Calendars, January 1900 and 2000 :-

        1   2   3   4   5   6   7   8   9   10 ...
1900 : Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed ...
2000 : Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon ...

Systems that fell back a century therefore have the weekends two days early.
They will also have Summer Time and many Church and secular holidays wrong.
Beware of automatic controls.

14 :-

UK and foreign general holidays near Y2k: my best estimate so far; most foreign ones were guessed only (RSVP) :-

---------------------- 1999 ---------------   ----------- 2000 ------
Dec:  22  23  24  25  26  27  28  29  30  31, Jan: 01  02  03  04  05
     Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri      Sat Sun Mon Tue Wed

E+W:  W   W  1/2 w/e w/e Hol Hol  W   W  Hol      w/e w/e Hol  W   W
NI :                                  <--- as E+W ? --->
Sco:  W   W   W  w/e w/e Hol Hol  W   W  Hol      w/e w/e Hol Hol  W

Irl:  W   W  1/2 w/e w/e Hol Hol  W   W   W       w/e w/e Hol  W   W

NL :  W   W   W  w/e w/e  W   W   W   W   W       w/e w/e  W   W   W

EU :  W   W   ?  w/e w/e  W?  W?  W   W   W       w/e w/e  W   W   W

Can:  W   W  1/2 w/e w/e Hol Hol  W   W   W       w/e w/e Hol  W   W
USA:  W   W* Hol w/e w/e  W*  W   W   W  Hol      w/e w/e  W   W   W

ISO: ----- Week 51 -----|----------- Week 52 ------------|--- Week 1 ---

1999-09-06 : Updated, esp. Sco, from 1999-2000 IoP diary.
W/h: Working day, though half-holiday for many.
"Holidays aren't uniform over Scotland - different places have different odd days here and there, but over the new year period they are relatively standard".
* "In the USA, banks and exchanges will open Dec 23 and 27, but either may be a state or local holiday in some locales. Some companies will be closed." URL?
* See also Annual Holiday Dates.

15 :-

I hear that in Motorola's VERSAdos Multi-tasking Operating System (UNIX look-alike), at 31 December 2043, the system clock rolls-over to 1 January 1980, because the 'Telefile' Time/Date 4 byte (32 bit) format is used, where the MSB 6 bits are used for years from 1980 (i.e. 1980 + 0 - 63 years expires at 2043). (Telefile format : y6 m4 d5 h5 m6 s6)

This probably obscure operating system is still used by a 1980's developed SCADA system from Leeds & Northrup (Australia) Pty Ltd of Sydney (now Foxboro-LN Pty Ltd of Sydney), their LN2068 SCADA System (or LN700 in USA). It is the current SCADA system used by a number of power utilities in Australia and New Zealand, Asia and USA.

16 :-

Note that it will be Shabbat JRS - Critical and Significant Dates - J R Stockton

To Foot

Critical and Significant Dates .

No-Frame * Framed Index * Frame This

Links within this site :-

Merlyn Home Page - Site Index, E-Mail, Copying
This Page :-
- Conditions of Use and Citation
- Critical Dates, with 0001, 1999, 2000, 2001, 2012, 2013, 2014, 2038, and Notes (including Holidays) :-
  - The List of Dates
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- Repeated Risks :-
- Periodic Events :-
  - Critical Periods
  - Other Periods
Related Pages :-
- Critical Times Calculator (not public)
- Year 2000 set
For more date/time pages, and links, see Date and Time Index and Links

Usage Counter Those benefiting from this site are invited to contribute to some local charity.

Conditions of Use and Citation

Please do not fetch this Web page (or others of mine) by automated subscription; that wastes my resources. Because of this abuse, I may sometimes change the name or offer only critdate.zip.

Copying

Material on this page has neither been copied nor derived from Warren, McVeigh & Griffin, Inc..

Citation

Normal Web links to and citations of this page are welcome (there is no need to ask).

Those intending citation in popular print or broadcast media are requested to consult me first about cacheing or mirroring, and about relative links.

Critical Dates

See also, at IET, Dates Potentially Causing Problems in Computer Systems from 2001-2100 (discovered in 2011).

When I receive E-mail information correcting or extending the list, I will assume permission to quote.

Links like _ are not intended for general use.

The List of Dates

Some are important; some are possibly just amusing - it is up to you to discriminate.

This List is not a prediction of disaster; it is an indication of when error may be prevented by sufficient care.

Software errors may have been fixed in later versions.

The more Critical Dates may have been chosen as trigger dates by virus writers - 2000-01-01, 2000-02-29, 2001.02.29, etc. - and may emulate date errors.

Some dates of non-computer origin are included. Historical dates are mainly limited to those of significance to UK history and culture.

For near-present Space dates, see Ron Baalke.

Virus trigger dates are NOT included - use a virus checker such as F-Prot (see PC Links Reference) and others.

Abbreviations should be obvious enough to those for whom they are significant.

2006-08-01 - New Warning

In general, I have mainly considered events relating to counting UP to particular numbers. There are also events relating counting DOWN; and those are less well predicted.

See 2006-05-13 and 2008-01-19 below as examples.

The Dates Themselves

Date Formats

Timing of Events

Some of these are local date/times; some are GMT/UTC or similar. I use GMT for legal GMT, with date changing at London mean solar midnight; the term UT might be confused with UTC.

Leap seconds may affect some dates, e.g. GPS rollover 1999, UNIX 2038.

The form a^b is used for "a to the power b" = a^b. The form mEe is used for m×10^e.

N.B. Two aspects of the year before AD 0001 are presented below, as BC 0001 and as ±0000 Astronomical.

B.C.

1.37E+10 years - The Big Bang, approximately
4.567E+9 years - Solar System formed
5509/09/01 Sat - Byzantine Empire, Creation and year-count start (Authors vary in detail; Julian?)
4714 11 24 Mon - (Gregorian) Julian Day 0 started at noon GMT, 24th Nov 4714 BC, Proleptic Gregorian Calendar
4713/01/01 Mon - (Julian) Start of First Julian Period
4713/01/01 Mon - (Julian) Julian Day 0 started at noon GMT, 1st Jan 4713 BC, Proleptic Julian Calendar.
Historians seem to treat it as starting at 0000h local - Chronological Julian Date, CJD
4236 -- -- --- - Alleged start of Egyptian Calendar - first recorded year in history. Note 21.1, 21.2
4004/10/22 Sat - (Julian) The Creation of the World, at six in the evening, according to Archbishop James Ussher of Armagh (1581-1656) - see Note 22
4004/10/23 Sun - (Julian) The First Complete Day
3761/10/07 Mon - (Julian) Anno Mundi 1, the origin of the Jewish Calendar, starting at the previous sunset. Sources may differ in detail : Note 20
3374/11/11 Mon - (Julian) And
3114/09/06 Mon - (Julian) And
3114/09/08 Wed - (Julian) Possible start of current Mayan Great Cycle (Long Count) (see AD 2012-12-23). Note 21.1, 21.2, 21.4
2637 -- -- --- - Legend: Emperor Huangdi invented the Chinese Calendar. Note 21.1, 21.2
1976/11/08 Wed - (Julian) CJD 1E6 (approximately)
0776 -- -- --- - Base of "Olympiad" dating - the first Games
0753 -- -- --- - The Founding of the City - base for Roman a.u.c. dates (March 1st)
0432 -- -- --- - Beginning of the First Metonic Cycle
0046 -- -- --- - (Roman) The "Year of Confusion", 445 days long; Julian Calendar decreed;
0045/01/01 Fri - (Julian) Julian Calendar began; but Leap Years were implemented wrongly (Calendar FAQ, S.2.1.1) before 8 AD (some say 4 AD)
0001/02/29 --- - (Julian) did not occur; as for AD 0004
0001/03/25 Tue - (Julian) The Day of the Incarnation/Annunciation, according to Dionysius Exiguus. Other Days follow naturally
0001/12/31 Fri - (Julian) B.C. ended with this day, the 365th of the year.

0000

0000 -- -- --- - Year number did not occur, except for Astronomers; like 4 AD, it was not Leap ; defective software may erroneously return some form like 0000-00-00, 0000-01-01, 0001-00-00, 0001-01-00, etc.
0000/01/01 Thu - (Astronomical Proleptic Julian)
0000-01-01 Sat - (Astronomical Proleptic Gregorian)
0000 02 29 --- - (Civil) did not occur; as AD 0004
0000/03/01 Wed - My preferred (Astronomical Proleptic Gregorian) Day Zero for calculation (except when I prefer to use CMJD).

A.D.

0001 -- -- --- - Fourth year of the 194th Olympiad
0001/01/01 Sat - (Julian) Start of A.D.; CMJD -678577
0001 01 01 Sun - (Civil) Start of A.D.; CMJD -678576; DCCLIIII AUC; 3761 A.M
0001-01-01 Mon - (Gregorian) Start of A.D.; CMJD -678575.
TTimeStamp Day 0/1 (Win9x).
TDateTime Day 1 (Delphi 1.0).
R.D. Day 1
Paradox Day 1 ?
0004 02 29 --- - (Civil) Not valid. 4 AD was *NOT* Leap (UNIX is wrong); earlier, Roman priests couldn't count correctly, and were still compensating here. Only general AD exception to 4, 4/100/400 year rules (apart from "AD 0", also not Leap)
0033-04-01 Fri - (Good Friday, Gregorian) Lunar Eclipse, Jerusalem
0033/04/03 Fri - (Good Friday, Julian) Lunar Eclipse, Jerusalem
0100-01-01 --- - Earliest date that can be directly input in systems where YY is mapped into YYYY
0100-01-01 Fri - (Gregorian) Earliest date value for Microsoft Jet database engine, VBScript, etc.
0200-03-01 Sat - Julian and Gregorian Calendar agreement starts
0284-08-28 Thu - (Gregorian; 6pm) Anno Diocletian 1 (ADio 248 ~ ADom 532)
0300-02-28 Wed - Julian and Gregorian Calendar agreement ends
0312 -- -- --- - Start of First Indiction, day varies
0325 -- -- --- - May-July, Council of Nicaea, Easter date rule
0622/07/15 Thu - (Julian) Sunset : First Moment of First Day of the Islamic Calendar
0622/07/16 Fri - (Julian) First Day of the Islamic Calendar, MuHarram 1, 1 A.H. Beginning of the year (month?) of the Hejira on the existing calendar. Some Islamic authorities say a day earlier. Note 21.2?
0622-07-19 Fri - Same day, Gregorian ; MJD -451561, CMJD 1948440
0888 08 28 --- - All digits even, last before 2000 02 02; cf. 1999-11-19, 3111-11-11
1000 ?? ?? ??? - Y1k; Vikings discovered America? :-(
1001 01 10 --- - Doubly palindromic as DDMMYYYY
1001 10 01 --- - Doubly palindromic as YYYYMMDD
1111 11 11 --- - Doubly palindromic
1221 12 21 --- - Doubly palindromic as YYYYMMDD
1380 08 31 --- - Last palindromic YYYYMMDD date until 2001
1582/02/24 Sat - (Julian) Gregorian Calendar decreed; for use from October, changes in Leap Year & Easter rules
1582-02-06 Sat - (Gregorian) The same day. Note: the Bull was dated MDLXXXI (1581).
1582 10 05 to 14 - (Civil) These 10 dates were skipped in Rome (at JD 2299160.5?), etc.
1582-10-15 Fri - (Gregorian) Lilian Day 1
1600/01/01 Tue - (Julian) Year began to begin on Jan 1, in Scotland (rest of Britain, see 1752 link)
1601-01-01 Mon - (Gregorian) ANSI COBOL 85 Day 1. Quattro Pro first day. Base filedate for Windows "Last Modified", etc. (64-bits of 100 ns)? MJD -94187
1605/11/05 Tue - (Julian) Guy Fawkes arrested previous evening
1700/02/29 Thu - A valid date, though only in still-Julian places; e.g. Great Britain and possessions
1710 10 02 to 1710 10 13 - Nova Scotia (Canada) had these civil dates twice
1712 02 30 Fri - Occurred in Sweden (and so, it seems, in Finland)
1751/01/01 to 1751/03/24 - Because of the change in the starting day of the year, these dates (which would have followed 1751-12-31) were never used in the English Civil Calendar
1752/09/02 Wed - Last Julian civil date in Great Britain
1752 09 03 to 13 - (Civil) These 11 dates were skipped in the British Empire
1752-09-14 Thu - First Gregorian civil date in Great Britain
1753-04-05 Thu - Start of UK FY 1753-54, moved from traditional Lady Day (Mar 25) because of calendar change above (but see Date Miscellany II)
1800-04-06 Sun - Start of UK FY 1800-01, a day later due to missing Feb 29 (ditto)
1805-10-11 Fri - Decreed that the RN day would in future start at local midnight - was the previous local noon - ships must have had a Long Day. Not implemented at Trafalgar
1841-01-01 Fri - Day 1 for ANSI MUMPS $Horolog function.
1852-02-29 Sun - Fred born. Possibly Fri, 4 years later
1858/11/05 Wed - GMT : MJD 0 by the Julian Calendar
1858-11-17 Wed - GMT : MJD 0 ; JD 2400000.5 ; JD 2400001 starts at noon UTC; CJD 2400001. Base date/time for DEC OpenVMS (VAX VMS), TOPS. See 0000-03-01 & Note 0
1867/10/06 Fri - Julian, CMJD 3257
1867 10 !! --- - Probable position of Alaskan date hiccup; the previous and following entries were consecutive local days
1867-10-18 Fri - Gregorian, CMJD 3257
1867 10 !! Sat - CMJD 3258 - Wikipedia starts Gregorian on Saturday 19th
1878-09-05 Thu - TJD -32768 : least 16-bit signed TJD
1880-08-02 Mon - Royal Assent to UK "Statutes (Definition of Time) Act", making GMT the legal time in Great Britain
1884-10-01 Wed - Start of International Meridian Conference, Washington, DC, USA.
Prime Meridian to be Greenwich, Greenwich Mean Time adopted, etc.
1884-11-01 Sat - End of Conference
1886-04-04 Sun - CMJD 10000; five digits needed
1899-12-30 Sat - Borland Delphi 2.0+ base date (Day 0) for TDateTime double (D1 used Day 1 = AD 0001-01-01 Gregorian); CMJD 15018. Also for other systems without the anomalous retrospective 1900-02-29, e.g. VBScript
1899-12-31 Sun - ICL George 3 (etc.) Day 0
1900.01.00 Sun - Excel 97 SP-1, Day 0
1900-01-01 Mon - 00:00:00 GMT, IBM mainframe common time zero; tick is 2^n µs
1900-01-01 Mon - At 00:00:00 GMT, NTP time zero (a seconds count; no leap seconds; 1900-02-29 omitted [2000-01-01 = Day 36524])
1900-02-28 Wed - CMJD 15078. Was followed by March 1st
1900.02.29 --- - Non-existent Leap Day, except in Lotus 1-2-3 and compatible systems (Excel 97 SR-1 Day 60, ...), and in still-Julian countries; and possibly in G&S. See 1899-12-30, and Leap Years
1900-03-01 Thu - Gregorian : CMJD 15079. Followed February 28th
1900/02/29 Tue - Julian Leap Day, CMJD 15091, Gregorian 1900-03-13 Tue. See in Leap Years
1901-01-01 Tue - Ada: type TIME defines years as being in the range 1901..2099
1901-12-13 Fri - 20:45:52 is where UNIX should go to from 2038-01-19; but I have read that systems can show Mon Jan -17 1902, -03:-14:-08 or 17:00:00
1904-01-01 Fri - Start of old Apple Mac time - Excel Day 0, Seconds 0 - see 2040
1925-01-01 Thu - The Astronomical GMT day now starts at midnight - had been the following noon - implying a Short Day yesterday
1927-05-18 Wed - 10000 days from 1899-12-30
1940-02-29 Thu - Fred's 21st Birthday :-)
1948-08-05 Thu - CMJD 2^15
1956-08-01 Wed - August 1, 1956 is the day that Apple restarts at when the battery dies, I was told. But
1956-08-27 Mon - About 20:36 is the time that Apple restarts at when the battery dies, reported observations
1958-01-01 Wed - CCSDS date/time code start (0h TAI) - spacecraft data
1960-01-01 Fri - Alleged to be an IBM 360 epoch? What counting? Start of SAS daycount
1967-12-31 Sun - Probable Day 0 of Pick
1968-01-01 Mon - Sun SPARC: SunOS, Solaris, BSD/OS, Linux: in RTC, YYMMDD=000101
1968-01-19 Fri - would be 2^31 seconds from 1900-01-01, incl. 1900-02-29. NTP MSB set.
1968-01-20 Sat - 2^31 seconds from 1900-01-01, excl. 1900-02-29. NTP MSB set
1968-05-24 Fri - Epoch of TJD, first TJD=0. NIST says TJD = MJD mod 10000. CCSDS says 4-digit TJD = MJD - 40000
1969-12-31 Wed - Displayed in the New World for a zero-value UNIX time_t, JavaScript (etc.?) date; see 1970
1969-12-31 Wed - Perl, etc., time failure result (23:59:59); "-1 seconds" - Note 11
1969-12-31 Wed - IBM 360 date failure, reported at Mitre
1970-01-01 Thu - MJD 40587. Delphi, etc., 25569. Base Date for UNIX, time_t, JavaScript (& Java), Perl and some implementations of C - GMT, so seemingly yesterday in the New World. Seconds/ms counts start
1970-01-01 Thu - A common Microsoft date-windowing breakpoint
1970-01-01 Thu - "Y2k"-class problem from one-digit years was observed
1971-02-15 Mon - Decimal-Day, U.K. coinage - end of £.s.d
1971-05-11 Tue - IBM 370 TOD clock flipped its top bit @11:56:53.685248 GMT. 1900-01-01 + 2^51 µs
1972-01-01 Sat - Formal start of UTC time scale and Leap Seconds
1972-01-19 Wed - 03:14:08, Mac system clock MSB flip
1972-02-29 Tue - First leap year for IBM's TSO (Time Sharing Option); login message gave date as March 0, 1972.
1972-06-30 Fri - 23:59:60 UTC, the First Leap Second of all
1972-08-16 Wed - 9999 days to year 2000. Problem with tape retention - mainframe JCL parameter LABEL=RETPD=9999 "save forever" hits Y2k
1973-03-03 Sat - UNIX time_t 100 Ms from 1970, at 09:46:40 GMT. 99,999,999 special? See 2001-09-09
1975-01-05 Sun - PDP-6 12-bit days overflowed (DECsystem-10)
1975-04-06 Sun - Day 96 of some year, probably '75/'76. PDP-11 DOS/BATCH used (sic) 12-bit dates, (year-base)×1000 + day_in_year (BE)
1978-01-01 Sun - Earliest possible Amiga system date
1978-01-01 Sun - PDP-8 OS/8 3-bit years (from '70) overflowed; fixed later in the year
1978-07-04 Tue - UNIX time_t $10000000 at 21:24:16 UTC
1979-12-01 Sat - Mainframes, string "000197AF" problem manifested (Cory H.)
1980-00-00 --- - (sic) Earliest possible MS-DOS file date
1980-01-01 Tue - Earliest valid MS-DOS file date. Earliest possible MS-DOS system date; DayCount=0
1980-01-01 Tue - The "x'000197AF' for x'0001980F'" year began
1980-01-04 Fri - Many older DOS PCs will reset to here or hereabouts when RTC year=00 is found (and for other RTC format errors)
1980-01-06 Sun - Start of first GPS Week 0, at 00:00:00 UTC
1980-12-31 Wed - IBM comms controller "Day 366" failure; cf. 1996
1982-10-15 Fri - Gregorian calendar 400-year full repeat began
1987 -- -- --- - US DST rule change
1987-01-01 Thu - Burroughs Unisys A Series system date - Note 5
1987-01-05 Mon - UNIX time_t $20000000 at 18:48:32 UTC
1988-01-01 Fri - Sun leap year bugs : Risks Digest 6.05/1, 6.09/3, 6.10/5, 6/11, 6.14/3
1989-09-17 Sun - See 2079-06-05; Delphi Day 2^15
1989-09-18 Mon - 2^15 days from 1900-01-01 - 16th bit flipped
1989-11-16 Thu - 2^15 days from 1900-03-01 - 16th bit flipped (MTS failed)
1991-01-01 Tue - Steltor's CorporateTime server's UNIAPI_TIME value zero at 0h GMT - minute count. Oracle bought Steltor
1991-11-24 Sun - IBM: see 1997-12-##
1992-01-01 Wed - Certain Olivetti PCs' calendars failed (3-bit years from '84?); also AT&T 6300s
1992-11-01 Sun - Tandem CLX microcode bug struck at 3pm local - Risks Digest 14.06/7
1995-07-09 Sun - UNIX time_t $30000000 at 16:12:48 UTC
1995-10-10 Tue - CMJD 50000 {VS=10}. Second TJD 0 (or TJD 10000)
1996-01-01 Mon - UNISYS mainframe 8-bit clock rollover
1996-01-01 Mon - MS-DOS CHKDSK /F, FILE*.CHK date bug appeared - (Year-1980) is 4 bits? (seen by me in DOS 3.30, 5.00, 6.20; also reported in 6.22) (SCANDISK seems OK)
1996-02-29 Thu - Penultimate Leap Day of the Second Millennium
1996-12-31 Tue - 1996-366 - Tiwai Point (NZ) smelter failure. Also "Iceberg" storage array failure
1997-01-08 Wed - Unisys CTOS application problem, reported as -
"OFIS Spreadsheet fails to load on every Wednesday & Sunday. OFIS Spreadsheet v2 has problems calculating the day of week from this date (workaround released)." For FAQ, see 2041
1997-04-07 Mon - 999 days to year 2000
1997-05-19 Mon - 10000 days from 1970-01-01 - some OpenVMS dating may have failed unless an ECO was applied
1997-11-02 Sun - Alleged in Y2k news : "HP's old computers are scheduled to roll over and die @ 1400gmt Nov. 4, 1997?". Used for FAA ATC - Note 1. Actually Nov 2nd
1997-12-## ??? - Reported: Possible IBM mainframe minute clock 24-bit rollover about then. But 1960-01-01 + 2^24 minutes is 1991-11-24 Sun 20:16.
1998 -- -- --- - Year "98" may have been a "signal"
1998-02-08 Sun - approx : 100 weeks to Y2k; a failure has been reported
1998-04-06 Mon - UK FY 1998-1999 started - no problem?
1998-07-06 Mon - Possibly "9876" might be a "signal" entry?
1998-08-19 Wed - 500 days to Y2k - Y2k Awareness Day campaign: proposed South African "National Awareness Day", "Y2k for Africa Day", and "World Y2k Awareness Day"
1998-09-09 Wed - Sometimes a "signal" date - cf. 1999-09-09
1998-10-01 Thu - 15-month lookahead (seemingly common) began to fail
1998-10-25 Sun - End of Summer Time, clocks went back
1998-10-26 Mon - Hubble Space Telescope 32-bit clock MSB set at 20:42:15 UTC; systems had been checked for signed usage (RB: 1998-10-25). One system affected (RB: 28th)
1998-12-01 Tue - One month look-ahead to "signal" year
1998-12-31 Thu - Last day before "signal" year
1999 - some 1999 dates may have equivalents in 1998.
1999 -- -- --- - Year "99" (or "999") may be a "signal"
1999 -- -- --- - NIST : MIM or MCMXCIX ?
1999-01-01 Fri - Start of the last year of the 1900s. One Year to Y2k itself
1999-01-01 Fri - Effective introduction of the (electronic) financial Euro (ex-ecu) within continental Europe - dual accounting. See Europe and Euro for its symbol
1999-01-01 Fri - Y2k failure in year-ahead predictions
1999-01-02 Sat - AIUI, the strict "Jo Anne Effect" window begins
1999-01-02 Sat - YYMMDD sorting with one-year look-ahead fails (or 1999-01-01)
1999-01-04 Mon - First working day of 1999, generally
1999-01-05 Tue - First working day of 1999, Scotland
1999-01-09 Sat - 1999-9 : 9th day of '99 (cf. 1999-04-09)
1999-02-01 Mon - YYMM sorting with one-year look-ahead fails (or 1999-01-01)
1999-02-05 Fri - Airline reservations: 330-day lookahead meets Y2k
1999-02-11 Thu - Day 90000 of the UK Gregorian Calendar
1999-03-02 Tue - MS-DOS daycount rollover to 7000; no effects predicted
1999-03-28 Sun - Start of European Summer Time, clocks go forward
1999-04-01 Thu - Start of Canadian & Japanese FY. Also for NY in USA
1999-04-04 Sun - Start of American Summer Time, clocks go forward
1999-04-06 Tue - Start of United Kingdom FY 1999-2000
1999-04-09 Fri - 1999-99 : 99th day of '99 (D. Scott Secor) - a "nonsense" or "marker" date? See 1999-09-09
1999-04-20 Tue - 255 days to year 2000. A byte holds values 0..255. The more significant byte of a word "days till 2000" becomes empty; programming slips may now show
1999-05-24 Mon - See 1999-05-31
1999-05-31 Mon - UK Spring Bank Holiday and US Memorial Day, last Monday in May. A version of MS Outlook uses the fourth Monday in May, and so is a week early some years. Affects other MS applications?
1999-06-01 Tue - Start of PhTWOday national dual running - "The Big Number".
Several UK areas (London, Southampton, Portsmouth, Cardiff, Coventry, Northern Ireland) had phone number changes. Mobile numbers also change from Sep 30.
London (0)1#1 xxx xxxx numbers (# in [7,8]) will become (0)20 #xxx xxxx.
Dual running in London ends 2000-04-22, q.v.; other areas later.
Oftel is now Ofcom
1999-07-01 Thu - Abolition of duty-free within EU (travel)
1999-07-01 Thu - Australian Financial Year starts. Also USA: 46 (?) States' fiscal Y2k starts, FY 2000; but NY=04-01, TX=09-01; AL,MI=10-01
1999-07-01 Thu - Y2k failure in half-year-ahead predictions
1999-07-05 Mon - 180 days before 2000-01-01
1999-08-01 Sun - Windows 98 "Office 2000 Beta expiry" bug starts. Upgrade RAGENT.DLL to version 9.0.2612 or later
1999-08-19 Thu - First EOW related update to the GPS Almanacs, at 2200 Zulu; updating takes 24h overall, and could affect users
1999-08-21 Sat - End of GPS Week 1023 (from 1980-01-06), 10-bit field "EOW" rollover (nominally at 0000h the next day; but, because of Leap Seconds, actually at 1999-08-21 23:59:47 UTC). USNO, gpsinformation.net.
It seems that most receivers are OK; some may lose lock for a few minutes at rollover; a few may not lock in Week #0 (mod 1024)
1999-08-22 Sun - See yesterday, if East of the Atlantic
1999-08-23 Mon - See 1999-08-30
1999-08-30 Mon - UK Late Summer Holiday, last Monday in August. A version of MS Outlook uses the fourth Monday in August, and so is a week early some years. Affects other MS applications?
1999-09-01 Wed - Start of FY for TX in USA
1999-09-09 Thu - Default "nonsense" or "marker" date in many data-entry screens - 9-9-99 may have been used as an indefinite "Purge" date - purge file overflow? See Randall Bart? Subsequently, data may be unprotected
1999-09-23 Thu - 99 days to year 2000
1999-09-30 Thu - Start of UK mobile phone number change dual running.
Dual running ends April 2001
1999-10-01 Fri - USA's federal government fiscal Y2k starts, FY 2000. Also for AL, MI in USA
1999-10-01 Fri - Y2k failure in quarter-ahead predictions
1999-10-01 Fri - Those changing from YY/M/D to YYYY/M/D may find that the field becomes too long as the month (or day) goes from 9 to 10. Note 2
1999-10-03 Sun - 90 days to Year 2000 - 90 day intervals are common (& 60,30)
1999-10-31 Sun - End of Northern Summer Time, clocks go back
1999-11-11 Thu - 1999 in Japan is eleventh year of Heisei; demand for railway platform tickets marked 11/11/11 11:11 seems to have crashed the system (Risks Digest 20.65)
1999-11-19 Fri - All digits odd, last until 3111-11-11; cf. 0888-08-28, 2000-02-02
1999-12 -- --- - Dec '99 may be a "Signal"
1999-12-01 Wed - One Calendar Month to Y2k itself. Monthly look-ahead fails
1999-12-24 Fri - Christmas Eve - Note 14, until 2000-01-05
1999-12-25 Sat - Christmas Day
1999-12-26 Sun - Boxing Day, traditionally; but nowadays Boxing Day is often the first weekday after Christmas
1999-12-27 Mon - Week 52 of 1999 starts, the last ISO week of 19xx
1999-12-27 Mon - UK Holiday in lieu of 25th
1999-12-28 Tue - UK Holiday in lieu of 26th
1999-12-31 Fri - UK Bank Holiday (Confirmed by HMG, 1998-06-03)
1999-12-31 Fri - Sometimes used as a special marker, such as a "Never Expires" date (IBM Tapes marked 99365 - all may expire today, or not; also 99366, 99999)
1999-12-31 Fri - Support for much software may cease after today
1999-12-31 Fri - Last working date for IBM CICS 3.3
1999-12-31 Fri - Last working date for versions of Intuit's Quicken online banking
1999.12.32 Sat?- Reported as sighted in a PC RTC. Watch out for such dates in data
1999.13.01 Sat?- Reported as sighted as a Netware file date. Watch out for such dates in data
1999-999 --- - (etc.) a better "special" date than Apr 9th ; = 2001-09-25 ; see 9999
1999.99.99 --- - (etc.) a better "special" date than Sep 9th ; = 2007-06-07 ; see 9999.
2000 -- -- --- - THE YEAR 2000 - an annus horribilis - Still the 20th Century, but some will say the 21st
2000 -- -- --- - Year "00" may be a "signal", e.g. "invalid"
2000-00-00 --- - As next:
2000.01.00 --- - Apparently, some systems have this - check its absence - Note 12
2000-01-01 Sat - CMJD=51544. DOS day 7305. One year to M3 and c21
2000-01-01 Sat - Final stage of compulsory metrication in UK (apart from roads, beer, ... ?)
2000-01-01 Sat - Australian map grid change
2000-01-01 Sat - It has been asserted that some computer systems (S/36? S/38? AS/400 B-10?) will not work after 1999; the IBM site referred
2000-01-01 Sat - AS/400 internal hardware clock MSB flips, see 2071-05-10
2000-01-01 Sat - Reported that GMS/SMS crashes a PC today
2000-01-01 Sat - Notes 2, 7, 8, 9, 13, 16
2000-01-02 Sun - (ff.) Completion of first-day processing now possible
2000-01-03 Mon - Start of ISO Week 1 - first week in 20xx, 1999W52 clean-up now possible
2000-01-03 Mon - First Business Day of 2000 (USA). UK Holiday :-)
2000-01-04 Tue - First Business Day of 2000 (most of UK)
2000-01-05 Wed - First Business Day of 2000 (Scotland)
2000-01-05 Wed - Note 2
2000-01-06 Thu - Note 13
2000-01-07 Fri - Last working day of first week of 2000, in most countries. Weekly batch work, payday
2000-01-10 Mon - Note 2
2000-01-12 Wed - Note 2
2000-01-17 Mon - First USA Monday holiday (MLK day) - Note 13
2000-01-31 Mon - Last day of first Calendar Month of 2000. Monthly batch work. Tomorrow, clean-up for the first month of 2000 begins
2000-01-32 ff. - Sightings of these have been reported
2000-02-02 Wed - All digits even, first since 0888-08-28; cf. 1999-11-19, 3111-11-11
2000-02-15 Tue - USA employees' 1999 W2 forms are due out.
2000-02-28 Mon - Not month-end
2000-02-29 Tue - This valid date is not expected to occur by everyone; some major software is or has been wrong here. One reason is missing the 400-year rule; another is using full rules on a YY date. Check that March 1st is next.
Examples : RFC2030 is wrong; JTIDS (Mil; Link 16) tables were said by doncio to err (fixed?); Excel 2000 (pdf); IBM VM/ESA 2.3 needs an APAR [PTF#UM29184]); SCO UNIX 3.3? I've seen it said that Motorola CPU RTCs use 4+100 rules, so omit this day; so far, I remain unconvinced
2000-02-29 Tue - Henceforth, unless fixed, MS DHCP client date error - IP leases a day too old. Q230173
2000-02-29 Tue - It has been said that un-upgraded HP 300 Basic entered dates fail after today.
2000-02-29 Tue - It has been said that some PDP-11 computers will not boot after this date - a diagnostics bug. But Mentec did not refer to this; and another expert (RHS of PA) says that it is just that the 11/93 & 11/94 consoles get the Leap Year rule wrong
2000-02-29 Tue - For this day, Her Majesty should NOT have been sending any of her traditional messages (were telegrams) to centenarians.
2000-02-30 --- - "Hollywood Squares" (TV game show) wrongly claimed that 2000-02-30 would exist
2000-02-31 --- - With 2000-02-30, reportedly seen in some PC software
2000-03-00 --- - Reportedly, VxWorks (Wind River Systems) has this (at least in some versions and on some platforms) instead of 2000-02-29
2000-03-01 Wed - Follows 2000-02-29. Some leap year errors may not have shown yesterday
2000-03-01 Wed - UK Data Protection Act 1998 comes into effect
2000-03-01 Wed - From 1918-03-01, first day for which certain implementations of Zeller's Congruence have negative-mod-7 error
2000-03-25 Sat - Possible UK/EU Summer Time error, since 1900-03-25 was Sunday. The Boat Race, 16:10 (GvI 15:40). :-(
2000-03-26 Sun - Start of Summer Time (UK, EU, ...)
2000-04-01 Sat - 2Q'00 starts, 1Q'00 clean-up - Last April Fool's Day of the Millennium. Possible US DST error, since 1900-04-01 was Sunday
2000-04-02 Sun - Belated Start of Summer Time (USA, ...)
2000-04-05 Wed - End of United Kingdom FY 1999-2000, which was a Leap Year
2000-04-06 Thu - Start of United Kingdom FY 2000-2001
2000-04-06 Thu - Introduction of different taxation in Scotland?
2000-04-09 Sun - The hundredth day of the year (cf. 1999-04-09). Note 2
2000-04-15 Sat - USA taxpayer panic day (W2 forms are due back to govt)
2000-04-15 Sat - Systems thinking that it is now 1900 will think that today is Easter Sunday
2000-04-22 Sat - "PhTWOday" (Easter Saturday) - "The Big Number" - national dual running ends (see 1999-06-01).
Several UK areas have had phone number changes.
London (0)1#1 xxx xxxx numbers (# in [7,8]) have become (0)20 #xxx xxxx.
The change from 7-digits to 8 digits for local London numbers is on this day.
See also Clive Feather for phone info.
Oftel is now Ofcom
2000-04-23 Sun - St. George's Day, and Easter Sunday. Bard's anniversaries
2000-04-30 Sun - First month of Y2k finishing in a weekend. Note 16
2000-04-30 Sun - USA quarterly 941 withholding tax is processed (on a Sunday?)
2000-05 -- --- - Solar Max now expected around mid-year - Note 17
2000-06-28 Wed - the 180th day of 2000
2000-07-14 Fri - QEQM = QV, previous longest Q in this country
2000-08-04 Fri - QEQM = 100 celebrated
2000-08-05 Sat - UK phones - Cardiff - 01222 becomes 029 20
2000-08-05 Sat - UK phones - Coventry - 01203 becomes 024 76
2000-08-27 Sun - Early Australian Summer Time, for Olympics
2000-09-** *** - Certain consequences of over-celebration are starting to emerge ..
2000-09-01 Fri - Note 2
2000-09-02 Sat - UK phones - Portsmouth - 01705 becomes 023 92
2000-09-02 Sat - UK phones - Southampton - 01703 becomes 023 80
2000-09-06 Wed - Note 2
2000-09-09 Sat - Sometimes a "signal" date - cf. 1999-09-09
2000-09-10 Sun - Note 2
2000-09-13 Wed - Note 2
2000-09-16 Sat - UK phones - Belfast - 01232 becomes 028 90
2000-09-16 Sat - UK phones - other Northern Ireland - 01xxx yyyyyy become 028 ##yy yyyy
2000-09-27 Wed - Note 2
2000-09-30 Sat - USA federal FY ends
2000-10-01 Sun - Note 2
2000-10-04 Wed - Note 2
2000-10-10 Tue - Note 2. (VS=VS?)
2000-10-11 Wed - Note 2.
2000-10-14 Sat - UK phones - London - 0171 & 0181 stop working today. For those 01x1 yyy zzzz use 020 xyyy zzzz
2000-10-28 Sat - False Summer Time ends, on 1900 days
2000-10-29 Sun - Northern Summer Time ends
2000-12-30 Sat - Allowing for the errors of the Julian Calendar, the Third Millennium of our era, when the Sun has returned to its starting point with respect to the Earth for the 2000th time, starts at around 03:00:00 today
2000-12-31 Sun - 366th day of year, possibly unexpected; see 1996. Norwegian train failures!
2000-12-31 Sun - Like 1972, 2028, ..., contains 54 Sun..Sat calendar weeks or parts thereof; this day is the 54th week
2000-12-31 Sun - Year-End processing
2000-12-31 Sun - London - low tide, 23:00 approx.; caveat

2001 - All is not yet clear ...
2001 -- -- --- - For the first time in a century, last year is "00"
2001-01-01 Mon - Third Millennium A.D. and Twenty-First Century A.D. start. UK bicentennial; AU centennial
2001-01-01 Mon - Applications hard-coded for the 20th Century proper now fail
2001-01-01 Mon - Reported that Tandem systems overflow; no details. Reported that Y2k fix to 'Automated Storage Manager' ends; no URL given
2001-01-01 Mon - Fixes that just change 1900 to 2000 fail. Allegedly, this may include versions of Windows, 98 & NT
2001-01-01 Mon - New date interpretation ambiguities start, as YY enters the ranges of MM & DD.
* Forms YY-MM-DD, DD-MM-YY & MM-DD-YY; general.
* Forms MMM DD & MMM YY, DD MMM & YY MMM; especially food dating
2001-01-01 Mon - See 2009-09-09. 010101 has been used as a marker for "unknown DoB"
2001-01-20 Sat - Is 20012001 YYYYDDMM or DDMMYYYY, not that it matters?
2001-02-20 Tue - Is 20012002 YYYYDDMM 20 Feb 2001 or DDMMYYYY 20 Jan 2002? Is 20022001 YYYYDDMM 20 Jan 2002 or DDMMYYYY 20 Feb 2001?
2001-02-29 --- - Will not exist; but check software
2001-03-25 Sun - UK/EU Summer Time starts, 01:00 GMT
2001-04-?? ??? - End of UK mobile phone number change dual running
2001-04-01 Sun - (& MJD52k) US DST starts 0200h local time. Reported that MS Visual C++ RTL gets an error whenever April 1 is a Sunday, and starts its DST a week late. Affects Windows applications. See Risks Digest 21.34/9 for an occurrence in 2001. Fix issued
2001-04-05 Thu - End of United Kingdom FY 2000-2001, which was not a Leap Year
2001-04-08 Sun - See 2001-04-01
2001-04-19 Thu - 04:25:21 GMT is UNIX time_t 987654321
2001-04-28 Sat - UK mobiles and pagers - numbers now start "07"
2001-09-01 Sat - New UK vehicle numbering, AA99 BBB. DVLA Local Tag list
2001-09-09 Sun - UNIX time_t 1 Gs from 1970, at 01:46:40 GMT. 999,999,999 special? Also JavaScript (+Java) 1 Tms - Note 10, Note 18
2001-09-25 Tue - = 1999-999
2001-10-02 Tue - First palindromic YYYYMMDD date since 1380
2001-10-28 Sun - UK/EU Summer Time ends, 01:00 GMT
2001-11-24 Sat - UNIX time_t 2^24 minutes, 20:16 GMT
2001-12-31 Mon - Lotus Organizer 1,0, 1.1 finish today
2001-12-31 Mon - as 2002-12-30
2002-01-01 Tue - Euro cash circulation starts within much of continental Europe ("Euroland"). EU, less Denmark, Sweden, UK
2002-02-?? ??? - About mid-month, Y4.7k of the Chinese Huangdi Era. Huangdi 4697-10-13, launch of Chinese unmanned spacecraft, 1999-11-20
2002-02- . . . - Euroland termination of national tangible currencies this month (Daily Telegraph, 2002-01-01, p.4) - possible last days :-
- 2002-01-27 Sun - Netherlands
- 2002-02-09 Sat - Ireland
- 2002-02-17 Sun - France
- 2002-02-28 Thu - Austria Belgium Finland Germany Greece Italy Luxembourg Portugal Spain.
2002-02-20 Wed - Doubly palindromic in the UK as DDMMYYYY, and ISO but not US; and in the evening, 20/02/2002 20:02:20.02 is quadruply so, as far as the digits go. It is CMJD 52325, also palindromic
2002-02-28 Thu - Euroland termination of national tangible currencies completed (Daily Telegraph, 2001-01-03, p.17)
2002-05-27 Mon - NOT the UK Spring Holiday
2002-06-03 Mon - Queen's 50th Anniversary holiday in UK
2002-06-04 Tue - A standard UK holiday, displaced 8 days
2002-06-30 Sun - Effective termination of dual accounting with pre-Euro currencies within continental Europe
2002-07-01 Mon - Original finish of withdrawal of traditional money in continental Europe
2002-09-14 Sat - 250th anniversary of the start of the Gregorian Calendar in Britain. Apart from me, no-one seems to have noticed
2002-12-30 Mon - A DOS GAWK, using library strftime, has an ISO week number error. Example: Mon/Tue/Wed, when in Dec 29-31, should be in Week 01. Many years affected. Other software perhaps likewise
2002-12-31 Tue - Ditto
2003-01-01 Wed - Some DEC Basics put (Year-1970)×1000+DayOfYear in a 16-bit integer - this now fails, being 33001, and so >32767
2003-01-01 Wed - Burroughs Unisys A Series system date - Note 5
2003-08-28 Thu - Or thereabouts - first difference caused by new Saudi rules for Islamic month-length, from AH 1423. JAS
2003-11-28 Fri - At about GMT 00:00 or 24:00 (reports are unclear), GPS 8-bit week rollover since last Leap Second at 1998-12-31 23:59:60 Thu; a bug in Motorola Encore receivers gets 29th for a second of the 28th. Risks Digest 22.94/3 refers
2003-12-29 Mon - VBScript, as 2007-12-31
2003-12-31 Wed - Last date for DEC RT-11 file system, 5-bit year from 1972=0. VXworks
2004-01-01 Thu - Alleged Canvas 3.5 Mac "Year 2004" bug; 100 years from 1904. See Risks Digest 23.50/3, 23.51/7, and 2004-08-31 below
2004-01-10 Sat - UNIX time_t $40000000 at 13:37:04 UTC. See Risks Digest 23.12/3 and 23.13/9,11 for resulting failures. Affects Turnpike message-IDs
2004-02-29 Sun - First "Leap Day" of c21 & M3; Risks Digest 23.25/1, 23.29/8 refer to failure cases. Displays of some GM Pontiacs affected
2004-05-01 Sat - EU enlargement :- Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia
2004-07-17 Sat - GPS Receiver Almanac Rollover, 256 weeks after GPS 1024-week rollover
2004-08-31 Tue - 12:30, Mac Canvas 3.5 expiry, patchable. See Risks Digest 23.51/7
2004-10-02 Sat - @21:24:16 local, date rollover stops "stone" file system - Discreet, Montreal. Cause not known. Unix/Linux/?
2004-12-31 Fri - 2004-366 - cf. 1996-366
2005-??-?? ??? - "Some *really* old versions of UNIX (e.g. 16-bit BSD) die in 2005."
2005-06-01 Wed - London telephone 020 3xxx xxxx release by Ofcom; issue to customers expected in Autumn 2005. NOT 0203 xxx xxxx
2005-11-29 Tue - 04:53:20 GMT : 212 Gs from JD 0.0
2005-12-31 Sat - 23:59:60 UTC : first Leap Second for 7 years
2006-05-13 Sat - 01:27:28 GMT : Unix Epoch end (2038) minus 1 Gs - many AOLServer web servers failed - see Risks Digest 24.34/3
2006-10-29 Sun - US DST ends today, not next week
2006-11-05 Sun - Safe to update US DST code for 2007?
2006-12-31 Sun - HP3000, End Of Life
2007 -- -- --- - NA DST rule change 2006/07 - US CA BM BS TC
2007-??-?? ??? - UK telephone code 03 to be introduced
2007-01-01 Mon - Slovenia adopted the Euro
2007-01-01 Mon - Book Numbering : nominal start of ISBN-13 - Checker
2007-01-01 Mon - "USA FAA computers fail, 32 years from 1975". TZ? 2006?
2007-03-01 Thu - US DST rule change effective
2007-03-11 Sun - First earlier DST start in NA
2007-04-01 Sun - UK MSF 60kHz time signal moved from Rugby, Warwickshire to Anthorn, Cumbria
2007-04-01 Sun - First unexpected DST not-start in NA
2007-04-06 Fri - Good Friday and start of UK Financial Year - 3.2 applies
2007-05-19 Sat - MS-DOS CLOCK$ daycount 10000 - no effect?
2007-06-07 Thu - = 1999-99-99
2007-08-09 Thu - CMJD 54321
2007-09-12 Wed - Ethiopian (Ge'ez) calendar, 2000/01/01 - Y2k
2007-10-28 Sun - First unexpected DST not-finish in NA
2007-11-04 Sun - First later DST finish in NA
2007-12-20 Thu - QEII = oldest monarch in this country
2007-12-31 Mon - Also 2003-12-29, 2019-12-30, and every 28 years after in c.21 : Some VBScript DatePart give wrong ISO Week Number - see in VBScript Date and Time 2. Error seen both in Web pages and in WSH; still present in Vista
2008-01-19 Sat - 30 years before 2038-01-19 - mortgage look-ahead?
2008-02-29 Fri - "Leap Day"
2008-03-23 Sun - Easter Sunday was unusually early (previously this day in 1913 & next in 2160; earliest possible date, March 22, 1818 & 2285). Still in EU Winter Time!
2008-12-31 Wed - 2008-366 - cf. 1996-366
2009-01-01 Thu - NOAA: Termination of satellite processing of distress signals from 121.5/243 MHz emergency beacons. Use 406 MHz
2009-01-20 Tue - POTUS change - noon EST
2009-02-13 Fri - 23:31:30 GMT is UNIX time_t 1234567890
2009-09-09 Wed - 090909 is another possible valid nonsense or marker date; as with, of course, other 0x0x0x & 1x1x1x dates, or anything with YY small
2010-01-01 Fri - Y2.01K
2010-01-01 Fri - Beware of writing 20010
2010-01-01 Fri - There will be some who have coded only for Years 200#.
2010-01-01 Fri - Beware of those who have coded YY in Hex or BCD, then somehow use 2016 for 2010. Risks Digest 25.89
2010-01-01 Fri - Sorting YYMMDD decade-reversed covers 1990-2009 only
2010-01-01 Fri - Reported ANSI C library overflow. Very dubious. RSVP if you can explain it
2010 02 29 --- - non-existent. See BBC
2010/03/22 Sun - Orthodox (Julian) Easter Sunday is on the earliest possible date (2010-04-04)
2010-12-25 Sat - CMJD 55555
2011-01-01 Sat - Y1C. Taiwan Dynasty Date (from China; and North Korea) reaches three-digit years. Risks Digest 25.91
2011-04-29 Fri - Royal Wedding Public Holiday, UK
2011-09-14 Wed - @01:46:39 UTC less leap seconds, GPS 999999999 seconds
2011-11-11 Fri - Seen as a "marker" date - cf. 1999-09-09. Contains 11/11/11 11:11:11
2011-12-30 Fr1 - Samoa (non-US) and Tokelau omit this date, so moving the International Date Line.
2012 -- -- --- - Like 2028, but for Mon..Sun weeks; contains 54 calendar weeks or parts thereof. Also 1984, 2040, ..
2012-02-29 Wed - "Leap Day"
2012-05-28 Mon - NOT the UK Spring Holiday
2012-06-04 Mon - Queen's 60th Anniversary holiday in UK
2012-06-05 Tue - A standard UK holiday, displaced 8 days
2012-07-13 Fri - UNIX time_t $50000000 at 11:01:20 UTC
2012-12-21 Fri - Alleged end of World, Mayan Calendar (Long Count 13.0.0.0.0); failed. Might be December 2023; opinions differ
2012-12-31 Mon - 2012-366 - cf. 1996-366
2013-03-31 Sun - EU Summer Time starts on Easter Sunday
2013-04-01 Mon - Reported iPad2 calendar Month bug
2015-09-05 Sat - Apollo/HP 32-bit rollover Note 1
2015-09-09 Wed - QEII = QV, previous longest-regnant in this country
2016-??-?? ??? - See 2010
2017-01-20 Fri - Presumed POTUS change - noon EST
20??-??-?? ??? - Introduction of the Euro in the UK ???
2019-01-01 Tue - First probable confusibility by value of the first two digits of the date between YY and YYYY forms
2019-03-01 Fri - Until 2100-03-01, last day for which certain implementations of Zeller's Congruence have negative-mod-7 error
2019-03-24 Sun - On proposed Aleppo rules, first Easter date differing from Gregorian (2019-04-21) - see Note 23
2019-04-07 Sun - Second GPS week rollover just before today, UTC
2019-06-06 Thu - MUMPS day 2^16
2019-12-30 Mon - VBScript, as 2007-12-31
2019-12-31 Tue - YY-date limit of Microsoft Excel 95. MS NT 4.0 fails after today if the RTC Century byte is "19"? Windows NT boot windows into 1920-2019?
2020-01-01 Wed - Half a century after UNIX/Java* Epoch; date windowing failures possible
2020-01-01 Wed - Henceforth, Mac (System 6.0.4+) Date & Time control panel cannot set current date
2021-01-14 Thu - UNIX time_t $60000000 at 08:25:36 UTC
2023-02-25 Sat - Third TJD 0; CMJD 60000
2024-11-09 Sat - MS-DOS CLOCK$ daycount 16384 - no effect?
2025-12-31 Wed - Versions of Intuit's QuickBooks for DOS - dates fail at end of year
2026-01-19 Mon - CCSDS 32-bit time code MSB sets 03:14:08 TAI, 2^31 seconds from 1958-01-01 (q.v.)
2026-06-29 Mon - Day 100000 of the UK Gregorian Calendar
2027-??-?? ??? - Asteroid 1999 AN10 approaches Earth; closest 0.00259(1) AU (lunar distance)
2027-12-31 Fri - Versions of Intuit's Quicken, QuickPay 3 for Windows, and QuickBooks for Windows & Mac - dates fail at end of year. Also HP 300 Pascal?
2028 -- -- --- - Like 1972, 2000, 2056, ..., contains 54 Sun..Sat calendar weeks or parts thereof
2028-01-01 Sat - "1900 + a signed byte" and "1900 + 7 bits" year overflow - back to 1772 or 1900
2028-01-01 Sat - Systems Y2k-remedied by 28-year setback fail today
2028-10-26 Thu - Asteroid 1997 XF11 passes Earth
2029-07-18 Wed - UNIX time_t $70000000 at 05:49:52 UTC
2029-12-31 Mon - Common end of windowing interval - YY-date limit of Microsoft Excel 97
2030-01-01 Tue - Half a century after MS-DOS file date Epoch; date windowing failures possible
2031-01-01 Wed - From HP-UX 10.20 'at' manpage: 'at' will not schedule jobs beyond the year 2030. That's local time
2031-12-31 Wed - Last date for Palm Pilot handheld
2033-05-18 Wed - UNIX time_t 2 Gs from 1970, at 03:33:20 GMT. 1,999,999,999 special? Also JavaScript (+Java) 2 Tms - Note 10
2034-01-01 Sun - Share/43 rolls back to 1970
2034-03-01 Wed - Safari JavaScript date string conversion error of one day, seen in version 5.0.3 to 5.1.7 in WinXP sp3, for this date until 2100-02-28
2034-09-30 Sat - Time overflow in some ancient UNIX, which was fixed long ago. Genuine, but no longer significant. See 2038
2035-12-31 Mon - at 2400h today, Microsoft's "Year 2000 statement of compliance timeframe" ends. Probably many MS products are affected, as at c. 2000
2036-01-01 Tue - Burroughs Unisys A Series system date - Note 5
2036-02-05 Tue - Note 6
2036-02-05 Tue - 06:28:16 local is 2^32 seconds from 1899-12-30 00:00:00; Delphi TDateTime can no longer be converted to dword seconds
2036-02-07 Thu - 06:28:16 GMT is 2^32 seconds from 1900-01-01 00:00:00 GMT; NTP timestamp overflows, possibly at 00:54:54 (IETF) (diff 20002 s), yesterday if 1900-02-29 included. Also TIME, SNTP. RFC 1305?
2036-02-07 Thu - Microsoft Word 2000 date sorting fails
2036-12-31 Wed - Date limit of Visual C++ (4.x) runtime library MS NT 4.0 fails after today if the RTC Century byte is "20"?
2037-01-01 Thu - Reported NTP overflow - implausible
2037-02-06 Fri - 06:28:16 GMT is 2^32 seconds from 1901-01-01-00:00:00 GMT
2037-12-31 Thu - Code using "C" libraries may fail after today. WS_FTP (some editions) Year 2000 support ends
2038-01-01 Fri - From HP-UX 11.00 'at' manpage: 'at' will not schedule jobs beyond the year 2037. That's local time
2038-01-01 Fri - Apple Rhapsody OS was said to fail. I can no longer locate this date at Apple; I think it should be as next.
2038-01-19 Tue - 32-bit UNIX/POSIX : 2^31 seconds from 1970-01-01, time_t MSB sets @03:14:08 GMT, and signed time_t<0 or time_t=-1 (the latter may be right; but the former may be used) is an error marker - "C" libraries: Note 4; Porquet page; Year 2000 Programming. See 1901-12-13.
"Version 3.1 of InterSystems' Cache (www.intersys.com) crashes on January 19, 2038. Related to C calendar library problem A fix is reportedly in the works."
2038-04-23 Fri - CMJD 2^16
2038-04-25 Sun - Easter Sunday is as late as possible this year (previous, this day in 1943)
2038-??-?? ??? - "World Cup namespace fills" (Soccer)
2038-11-21 Sun - Third GPS week rollover just before today, UTC
2039-09-18 Sun - Y5.8k Jewish starts at Sunday sunset. Tishri 1 (Rosh Hashanah), 5800
2040-01-01 Sun - Pick, possible limit???
2040-??-?? ??? - Alleged IBM S/390 STCK overflow ???
2040-02-06 Mon - At 06:28:16, old Apple Macs' longword seconds from 1904-01-01 overflows
2041-01-01 Tue - Reported "that IBM mainframe internal clocks will not go past the year 2041". Not yet confirmed.
2041-11-16 Sat - Unisys BTOS / CTOS Operating System - Clock will roll over at 2400h to 1952-03-01 - FAQ
2042-09-17 Wed - IBM 370 and successors, TOD clock overflow (long seconds (1.048576 s) from 1900) at 23:53:47 approx. 1900-01-01 + 2^52 µs
2044-01-01 Fri - MS-DOS : 2^6 years from 1980, 7-bit file date MSB sets
2044-01-01 Fri - Motorola VERSAdos : 2^6 years from 1980, 6-bit file date rolls to 1980 - Note 15
2046-01-01 Mon - Amiga system date failure
2046-06-08 Fri - BYTE says some UNIX password aging fails, 64^2 weeks from 1970. But see 2048-07-01
2047-09-19 Thu - CCSDS 16-bit day code MSB sets, 2^15 days from 1958-01-01 (q.v.)
2048-01-01 Wed - AD 2^11 starts - 12-bit signed overflow - PDP-8???
2048-01-19 Sun - Stratus VOS OS failure (1980-01-01 + 2^31 seconds)
2048-07-01 Wed - Some UNIX password aging fails; 64^2 weeks from 1970 (reported as June, or 2046 (q.v.)
2049-12-31 Fri - Microsoft Project 95 (and earlier) limit
2050-01-01 Sat - YY-windowing into 1950-2049 collapses
2057-09-17 Mon - If Pick Day 1 is 1968-01-01, this is Day 32768
2058-02-08 Fri - TJD +32767 : greatest 16-bit signed TJD
2059-09-19 Fri - 2^15 days from 1970-01-01. Signed overflow?
2060-??-?? ??? - Around now, present-type TLEs for artificial satellites may become ambiguous, as they use 2-digit years (YYDDD)
2060-01-01 Thu - The trick of using a two-digit year representation with the first digit Hex (98,99,A0,A1..F9) fails today If the digits are stored as nibbles, no more can be done; if as characters, 200 more years brings the end of Z9
2067-07-02 Sat - GRB numbering (yymmdd) becomes ambiguous (First : Vela GRB 670702)
2068-01-01 Sun - Sun SPARC: SunOS, Solaris, BSD/OS, Linux: in RTC, YYMMDD=000101 again
2069-01-01 Tue - POSIX standard assumes 1970 ≤ year < 2069 (gnulist)
2069-01-19 Sat - At 03:14:08, 2^31 secs of the Third Millennium
2069-09-18 Wed - 2^15 days from 1980-01-01 MS-DOS CLOCK$ daycount word MSB sets - no effect? Seemingly used in Oyster
2070-01-01 Wed - Centenary of 1970-01-01, the start of UNIX, C, etc., time_t, and of JavaScript time. Possible Y2k-type errors in year handling appear. But see 2038
2071-05-10 Sun - AS/400 internal hardware clock (42-bits of 1024 µs centred on start of 2000) rolls over at 11:56:53.685248 to 1928-08-23
2072-??-?? - "Exact Date TBD: Overflow of Milstar Operating System". Possibly GPS-UTC signed 8-bit overflow, year approximate
2078-12-31 Sat - Excel 7.0 - The Last Day, #65380 (Phil E); and Excel 95
2079-06-05 Mon - 2^16 days from 1899-12-30 = Day 0; Delphi TDateTime resolution halves for dates from here. Previous, in 1989, 1944; Next, 2258
2079-06-06 Tue - 2^16 days from 1900-01-01 = Day 1
2079-08-04 Fri - 2^16 days from 1900-03-01 = Day 1
2080-01-01 Mon - MS-DOS file dates, when displayed with two-digit years, are ambiguous if files may be dated today or later. Windows File Manager, set to ISO 8601 dates, drops 100 years from displayed file dates of 2080+. My Amstrad PPC640, bought in 1988, evidently cleverly windows YY into 1980-2079; so will now err on boot
2094-02-06 Sat - CCSDS 32-bit time code overflow 06:28:16 TAI, 2^32 seconds from 1958-01-01 (q.v.)
2096-01-01 Sun - As 2060, but for two Hex characters
2100-01-01 Fri - Y2.1K - will they never learn?
Most current PC BIOS run out of dates.
MS-DOS DIR renders filedate years 2100-2107 as 99.
Ada: package Ada.Calendar defines years as being in the range 1901..2099.
Many short-term Y2k fixes fail
2100.02.29 --- - Next non-existent February 29 in a year divisible by 4 ; first failure of plain "4-year" rule since 1900
(except for Greek Orthodox outside Greece, using Julian; and for the usual PC RTC);
End of 200 years of 28-year calendar repeat. Start of 100 years thereof
2100-03-01 Mon - Zeller, as 2000-03-01
2101-01-01 Sat - POSIX.1-1996 spec bug begins to act - UTC0-to-"seconds since the Epoch" 2100 leap error
2101-01-02 Sun - and probably every 400 years after : Some VBScript DatePart give wrong ISO Week Number - see via 2007-12-31
2106-02-07 Sun - 32-bit UNIX : 2^32 seconds from 1970-01-01, unsigned time overflows @06:28:16 GMT. Slightly earlier times (4h?) may be error markers. NFS rollover
2108-01-01 Sun - MS-DOS : 2^7 years from 1980, year field of file date overflows. Win3, Win95, etc. fail
2108-04-01 Sun - 08:04:02 - equivalent of MS-DOS ultimate datestamp $FFFFFFFF = 2107-15-31 31:63:62
2111-11-11 Wed - First zero-free YYYYMMDD in M3
2112-12-21 Wed - Doubly palindromic as DDMMYYYY
2114-10-15 Mon - Last Day (99999) for ANSI MUMPS $Horolog function customary 5-digit format.
2116-02-07 Fri - 2^32 secs from 1980-01-01 at 06:28:16
2128-01-01 Thu - EEPROM signed year rollover, Wikipedia; unsigned in 2256
2132-08-31 Sun - JD 2500000 starts at noon GMT
2132-09-01 Mon - CMJD 100000; sixth digit needed
2135-01-01 Sat - MMDCCCLXXXVIII : the Roman a.u.c. date field will be longer than ever before
2136-12-25 Tue - Newer 13-bit GPS week count first rollover, UTC ignoring omission of leap seconds (exact date uncertain)
2137-06-07 Fri - CCSDS 16-bit day code overflow, 2^16 days from 1958-01-01 (q.v.)
2147-10-28 Sat - TJD +65535 : greatest 16-bit unsigned TJD
2148-01-01 Mon - Rollover of 32-bit signed ((YYYY×100+MM)×100+DD)×100+SeqNo format, used for DNS serial numbers . Unsigned fails in AD 4295
2149-06-07 Sat - 2^16 days from 1970-01-01. Unsigned overflow?
2154-03-23 Sat - CDMA mobile phone (Americas, S Korea) system timer, 36 bits from 1980-01-06 UTC, overflows at 03:28:58.88 UTC exactly, ignoring leap seconds.
2155-12-31 Wed - Last possible "update date" for dBase format files (.dbf) : Y M D are each stored in a byte. ...
2156-01-01 Thu - "1900 + a byte" year overflow
2159-06-07 Thu - 2^16 days from 1980-01-01. MS-DOS CLOCK$: internal daycount would overflow
2173-10-14 Thu - 100000 days from 1899-12-30
2217-09-28 Sun - CMJD 2^17; original IBM halfword MJD use would fail
2239-09-29 Sun - Y6k Jewish, at sunset. Tishri 1 (Rosh Hashanah), 6000. Messiah expected, now or before
2247-01-01 Fri - Y3K a.u.c. starts (but on which exact date?)
2248-06-03 Sat - Risc OS / NC OS / ARM time rollover at 06:57:57.76 : unsigned 2^40 centiseconds from 1900-01-01 00:00:00. $0000000000, $FFFFFFFFFF may be markers.
2256-01-01 Tue - see 2128
2260-01-01 Sun - The trick of using a two-character year representation with the first character alphanumeric fails today (98,99,A0,A1..Z9); used on HP3000
2286-11-20 Sat - UNIX time_t 10 Gs from 1970, at 17:46:40 GMT. JavaScript 10 Tms
2400-02-29 Tue - Will exist - "100-year" rule overridden
2433-04-30 Sat - Last valid day for MMMM-DD notation based on 1600. I hear that MMMM-DD is sometimes used where YY-* will not serve. Also 2633, 2733
2576-08-08 Thu - CMJD 2^18; see 2217
2698-04-24 Sun - Last Gregorian Easter on the same day as Julian Easter (/04/06) of the same-numbered year
2738-11-28 Mon - Day One Million A.D. (approx)
2800-02-29 Tue - First Leap Day difference between Gregorian and Greek Greek Orthodox
2877-03-21 Sun - On proposed Aleppo rules, first March 21 Easter; -03-21 is impossible on Gregorian rules - see Note 23
2888-01-01 Thu - MMDCCCLXXXVIII : the Roman A.D. date field will be longer than ever before - 14 characters (1888 first to need 13; 3888 first to need 15; cvt_rome.pas)
2900-01-01 Fri - (Year-1900) exceeds %3d
2999-01-01 Tue - Windows CE FAT fails
3001-01-01 Thu - gmtime() localtime() functions in Visual C++ 2008 fail
3003-03-30 Wed - Doubly palindromic as DDMMYYYY
3111-11-11 Sat - All digits odd, first since 1999-11-19; cf. 0888-08-28, 2000-02-02
3173-10-13 Sat - Another Mayan Long Count end; world re-created
3199-12-31 Fri - Quattro Pro last day.
3268/01/01 Sun - (Julian date - 3268-01-23 Gregorian) start of Second Julian Period - see Calendar FAQ, and Peter Meyer. 28×19×15 years from JD 0 (Solar Cycle × Metonic Cycle × Roman Indiction)
3400-01-01 Wed - Microsoft's Visual Studio documentation: Jet database engine GUIDs algorithm avoids duplicates until AD 3400. (AD 1582-10-15 + 2^59×0.1 µs = Sat, AD 3409-07-08 22:40:30.3423488 ; perhaps should be AD 1582-10-15 + 2^60×0.1 µs = Mon, AD 5336-03-31 21:21:00.6846976)
3800-01-01 Wed - (Year mod 1900) diverges from (Year-1900)
3999-12-31 Fri - Last Day for some systems
4000-01-01 Sat - Roman year number is ill-understood after MMMCMXCIX
4000-02-29 Tue - Will occur, on the Gregorian calendar. I believe that 4000 was not going to be Leap in the USSR, and proposed not in Revolutionary France. The Greek Orthodox will agree with that, for different reasons
4047-01-01 Tue - As 2147, but for 1900-biased YYYY
4082-12-31 Thu - Last valid date according to a Y2k Glossary (first seen at NIST?); 1582+2500 & Gregorian Calendar error is about 1 day in 2500 years !!
4095-12-31 Sat - MS Word WordBasic date limit
4200-01-01 Wed - Gregorian Easter algorithms containing Year/300 or centade/3 are invalid from here - Zeller
4295-01-01 Tue - ??? BIND DNS serial number, YYYYMMDDxx, stored as 32-bit unsigned, wraps today: 2^32 = 4294 96 72 96,
4338-11-28 Mon - Cobol-85 Integer day 1000000 - exceeds 6-digit field
4500-09-01 Wed - Reported that the observed date limit for MS Outlook 2003 is about here
4501-01-01 Sat - 08:00:00 is reportedly a default date-time in Microsoft Outlook '98. End of Outlook Calendar
4712-12-31 Tue - Limit of Oracle?
4772-10-13 Fri - Completion of Mayan Great Cycle
5138-11-16 Wed - UNIX time_t 100 Gs from 1970, at 09:46:40 GMT. JavaScript 100 Tms
5336-03-31 Sat - see 3400-01-01
6053-01-23 Thu - @ 02:08, 2^31 minutes from 1970-01-01
9006-04-20 Sun - First Easter date for which Knuth's code has a problem with Epact : J D McC
9999-01-01 Fri - HTTP cacheing fails (or at year's end???)
9999-12-31 Fri - Last date for VBScript, etc.
9999-999 --- - (etc.) a marker date ; = 10001-09-25
9999-99-99 --- - (etc.) a marker date ; = 10007-06-07.
10000-01-01 Sat - Y10K - no - many problems recur - e.g. UNIX (etc.) ASCII runs out of YYYY, internal ".DBF" format fails?, PC RTC "century" CCYY rollover to 0000
10136-02-16 Thu - @ 04:16, 2^32 minutes from 1970-01-01
20010-??-?? ??? - An easy mistake for "2010", apparently
20874-05-01 Tue - In Y-M-D form, Islamic (A.H.) and Gregorian (A.D.) dates agree only from 20874-05-01 to 20874-05-30, after which the A.H. figures are the larger (subject to month-start uncertainty)
22666-12-20 Thu - CJD 10000000 (1E7) - JD 10000000 (1E7), from noon GMT
24867-03-24 Thu - 2^23 days from 1899-12-31 (ICL George 3 - the ICL 1900 was 24-bit; date error?)
24925-03-25 Sun - CCSDS 24-bit day code MSB sets, 2^23 days from 1958-01-01 (q.v.)
29228-09-14 Thu - at 02:48:05.4775808, 2^63 × 100 ns from 0001-01-01.0, .NET epoch
29601-01-01 Mon - Now or next year,
29602-01-01 Tue - Microsoft Windows NT file system (NTFS) fails
29940-##-## ??? - New Apple Macs' signed 64-bit time fails (OK since BC 30081)
30828-09-14 Thu - Win32, NT : signed (63-bit) time rollover at 02:48:05 (100 ns from 1601-01-01, assumed Gregorian)
31086-07-31 Sat - The internal DEC VMS time fails at 02:48:05.47. 2^63×100 ns from MJD 0. SLAC
32132-##-## ??? - Limit of my dateprox.pas about now; my longcalc.pas continues ....
Dates from here may be less reliable :-
32768-01-01 Mon - Start of Year 2^15, 16-bit signed integer limit
33658-09-27 Fri - UNIX time_t 1 Ts from 1970, at 01:46:40 GMT. JavaScript 1 Pms
34668-01-01 Wed - (Year-1900) + 2^15; 16-bit struct tm's tm_year fails
38434-08-17 Thu - IBM 370 STCKE instruction latest possible rollover @21:30:06.846976 GMT. 1900-01-01 + 2^60 µs
60056-05-28 Sun - Win32, NT : 64-bit time fails at 05:36:10 (100 ns from 1601-01-01, assumed Gregorian)
65536-01-01 Wed - 16-bit year code overflows, e.g. CCSDS
269078-08-08 Thu - JD 100000000 (1E8), from noon GMT
275760-09-13 Sat - +1E8 days from 1970-01-01 : JavaScript Date Object upper limit; lower limit is -1E8, -271821.04.20 Tue
685720-11-04 Mon - Second complete cycle of the Jewish Calendar starts about now
2733194-11-28 Mon - JD 1000000000 (1E9), from noon GMT
5874898-06-05 Thu - JD 2^31; 32-bit longint(JD) fails
5879611-07-12 Tue - Day 2^31, if 0001-01-01 Gregorian is Day 1
5881469-05-28 Fri - CMJD 2^31; 32-bit longint(CMJD) fails
11754508-12-14 Fri - JD 2^32, from noon GMT
27374357-12-21 Sat - JD 10000000000 (1E10), from noon GMT
3E08 approx. - Java time fails - (64-bit signed milliseconds from 1970) - AD 292,278,994-08-17 Sun 07:12:55.808 GMT
2147483648-01-01 Wed - Start of Year 2^31, 32-bit signed integer limit
3E11 approx. - UNIX 64-bit signed time_t fails (seconds from 1970) - AD 292,277,026,596-12-04 Sun 15:30:08 GMT (checked)
6E11 approx. - Tower of Hanoi completed (at one ring per second) : world ends (again)
5E16 approx. - AD 50,505,469,855,528,397-01-15 Wed, JD 2^64, from noon GMT
5E30 approx. - AD 5,391,559,471,918,239,497,011,222,876,596-04-18 Mon 16:02:08 GMT, UNIX 128-bit signed time_t fails
2E69 approx. - AD 1,834,652,618,499,343,590,337,415,746,119,712,509,834,124,421,548,072,260,582,352,567,003,896-01-25 17:06:08 GMT, UNIX 256-bit signed time_t fails. A Saturday
3.1...E19720 - 31...188450-03-24 Thu 09:06:08 GMT - UNIX 65536-bit signed time_t fails
2^1E80 approx. - As there are only about 1E80 particles in the observable universe, it has by now become impossible to write the date

Notes

0 :-

1 :-

2 :-

????-??-?? - The day on which "YY" is changed to "YYYY"
2000-01-01 - "01/01/100" - N.B. UNIX tm-year is (Year-1900).
2000-01-01 - "100-001" - (YY overflow & %3d daycount).
2000-01-05 - "Wednesday, 05/01/100"
2000-01-10 - "10/01/100" (format string "%d/%2d/%2d")
2000-01-12 - "Wednesday, 12/01/100"
2000-04-09 - "100-100" (YY overflow & %d daycount)
2000-09-01 - "01 September 19100"
2000-09-06 - "Wednesday, 06 September 19100"
2000-09-10 - "10 September 19100"
2000-09-13 - "Wednesday, 13 September 19100"
2000-09-27 - "Twenty-seventh [of] September 19100"
2000-10-01 - "01/10/100" (format string "%2d/%d/%2d")
2000-10-04 - "Wednesday, 04/10/100"
2000-10-10 - "10/10/100"
2000-10-11 - "Wednesday, 11/10/100"

In languages other than English ...
These may occur in 1999, if the date format has been changed from YY to YYYY.

3 :-

If in conjunction with time as %d:%d:%d, full length is not achieved until mid-morning.

4 :-

5 :-

Unisys A Series system date, various possible year overflows in 1987, 2003, 2036.

6 :-

Microsoft's help file: "mktime handles dates in any time zone from midnight, January 1, 1970, to midnight, February 5, 2036."

7 :-

In 2000 .. 2009, code using 'printf("Year=%d", yy)' will print 0 .. 9 rather than 00 .. 09; so 'printf("Year=%d%d", cc, yy)' will print 200 .. 209.

8 :-

Code using %2d to write tm_year = Year-1900 to a string, then moving the first two characters to a print field, will in 2000-9 give 10, 2010-9 give 11, ...

9 :-

Moving yyyy mod 100 (as opposed to yyyy - 1900) into a string with %d format will in 200X give an X followed by an unmodified byte.

10 :-

11 :-

12 :-

It's suggested that 2000.01.00 may lock Pentiums up irrevocably.

13 :-

Calendars, January 1900 and 2000 :-

        1   2   3   4   5   6   7   8   9   10 ...
1900 : Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed ...
2000 : Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon ...

Systems that fell back a century therefore have the weekends two days early.
They will also have Summer Time and many Church and secular holidays wrong.
Beware of automatic controls.

14 :-

UK and foreign general holidays near Y2k: my best estimate so far; most foreign ones were guessed only (RSVP) :-

---------------------- 1999 ---------------   ----------- 2000 ------
Dec:  22  23  24  25  26  27  28  29  30  31, Jan: 01  02  03  04  05
     Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri      Sat Sun Mon Tue Wed

E+W:  W   W  1/2 w/e w/e Hol Hol  W   W  Hol      w/e w/e Hol  W   W
NI :                                  <--- as E+W ? --->
Sco:  W   W   W  w/e w/e Hol Hol  W   W  Hol      w/e w/e Hol Hol  W

Irl:  W   W  1/2 w/e w/e Hol Hol  W   W   W       w/e w/e Hol  W   W

NL :  W   W   W  w/e w/e  W   W   W   W   W       w/e w/e  W   W   W

EU :  W   W   ?  w/e w/e  W?  W?  W   W   W       w/e w/e  W   W   W

Can:  W   W  1/2 w/e w/e Hol Hol  W   W   W       w/e w/e Hol  W   W
USA:  W   W* Hol w/e w/e  W*  W   W   W  Hol      w/e w/e  W   W   W

ISO: ----- Week 51 -----|----------- Week 52 ------------|--- Week 1 ---

15 :-

16 :-

Note that it will be Shabbat from before dusk 1999-12-31 to after dusk 2000-01-01. One should not expect observant Jews to want to participate either in program remediation or in Gentile celebration during that period (they're probably unenthusiastic about the whole affair, anyway). Also, they should consider reading 2000-04-30 above as 2000-03-31.

17 :-

The predicted Sunspot count peak was essentially flat over several months. Radio noise may affect communications. Geomagnetic storms may affect the National Grid. Solar flares peak probably within 2000..2002.
Monash, 1997-04-10? : "If current projections are correct, the sunspot maximum is currently estimated to peak in March of the year 2000. It must be noted, however, that predicting the month of maximum is even less certain than the sunspot number. The actual month of sunspot maximum could be as early as January 1999 or as late as June, 2001."
Harjit S. Ahluwalia, for 1998-04-03 : Abstract : The Planetary Index Ap, Ohl's Conjecture and the Predicted Size of Solar Cycle 23.

18 :-

I have seen a report that : Digital Unix had a bug where a timespec value (seconds and nanoseconds) was being checked to make sure the nanoseconds field wasn't more than 1 billion; instead, it was checking the seconds field, and as we hit the (Unix epoch) 1 billion second mark in 2001, the check would erroneously indicate it was invalid. (On the "documentation CD-ROM that came with Digital Unix 4.0D"; other Y2k errors were also fixed.)

19 :-

A system which is at the last valid day of any month MUST roll over at midnight to the first day of the next month. It SHOULD NOT (but, I think, not MUST NOT) be possible to set to a day in any month after the last valid day (and likewise before the first), and a system SHOULD if possible be designed not to allow this; but, if such a setting has been made, it is not at all clear what the setting should become at subsequent midnights - it's unlikely to be right, anyway, and it may be better to leave the error blatant and unambiguous by just incrementing the day field.

20 :-

The exact interpretation of the sources, and its representation on the Gregorian scale, are not necessarily always agreed.

Anno Mundi started on BC 3761/10/07 Monday (beginning at the previous Sunset [in Jerusalem] or 6 p.m.), Julian Calendar.
Whitaker's Almanac (1989; Pocket 2000) gives the epoch for chronology as Oct 7, 3761 BC. I make that CMJD -2052003, BC 3761 09 07 Gregorian, Monday. It is numbered as Day 2.
Remy Landau's Hebrew Calendar site; be careful with its notation (Proleptic Gregorian Astronomical), particularly before AD 1. My The Hebrew Calendar.

21 :-

(1) At NIST, USA : Ancient Calendars (a few pages), and From Sundials To Atomic Clocks (26MB PDF).
(2) At webexhibits, via Calendars through the Ages,
& Doggett, Calendars.
(3) At ScienceWorld : Weisstein.
(4) Thor Heyerdahl, Early Man and the Ocean, ISBN 0 04 572022 3, p.335 : "The zero date 4 Ahau 2 Cumhu .. our system .. 12 August 3113 BC". Gregorian?

22 :-

According to James Ussher, Anglican Archbishop of Armagh (1581-1656) in a posthumous edition (of Annales veteris testamenti a prima mundi origine deducti, 1650), The Annals of the World, iv, of 1658 : the Creation of the World occurred at the Equinox in October of BC 4004 (Julian). Note that Ussher seems, like others, to consider the evening of a day to be what we would now call the previous evening.

Ussher wrote : ... from the evening ushering in the first day of the World, to that midnight which began the first day of the Christian era, there was 4003 years, seventy days, and six temporarie hours - and AD 0001-01-01 0h minus 4003y 70d 6h is BC 4004-10-22 18h, i.e. 6 p.m. of Saturday 22nd October, BC 4004. That makes the first full day Sunday 23rd (Genesis, 1,5; the seventh day, of rest, is the Jewish Sabbath). Garden of Eden Time, presumably.

The date and time are often misquoted as the 23rd or 26th, and as 9 a.m.

The date, or the year, is often given in old Bibles : _ _ _

23 :-

World Council of Churches (Aleppo 1997), Towards a Common Date of Easter - also see Claus Tøndering's Calendar FAQ, and The Date of Easter Sunday

Coda

Doubtless I've missed a lot ... Leap seconds may be omitted above. Each "999" problem may be accompanied by a "1000" problem, and so on. For over three decades after 2000, it will not be possible to discriminate between YY/MM/DD and DD/MM/YY by inspection.

Cory Hamasaki (kiyoinc@ibm.net) wrote:
"... EXPDT=98000 or EXPDT=99000 or EXPDT=99365 which are fun dates, ..." which I think are specials in an expiry date field on some misbegotten systems ...

Also critical - the start of any regular period which first includes 2000 (the Jo Anne Effect) - for example corporate FY 1999-07-01..2000-06-30; or includes 1999. Note that while the UK national FY starts on April 6th, UK companies can choose their own FY, and I understand an April 1st start is common. Also that some bodies number their FY with its start year, some with its end year; the rational ones will, unless starting on Jan 1, use for example 1998-99 or 1999-2000 - which is a longer string.

When checking, verify Day-of-Week, especially across the Feb-Mar transitions, and at the ends of 2000.

Foreigners, beware side-effects of peculiar calendars, and North-South differences. Summer Time (Daylight Saving Time, DST) rules mean that time errors may arise from Date or Day-of-Week errors.

Any other date which used to seem far in the future (or past) may have been used as a "special" marker. Consider YY/MM/DD with YY=MM=DD≤12.

For many dates bearing an arithmetical relationship with the start of 2000, there may be corresponding problems with dates bearing the same relationship with 2038-01-19 (or other range-end dates) - cf. 2008-01-19.

Failure Modes

At MSU.

Repeated Risks

Some listed here as Y2k hay have correponding Y2038 risks.

Y2k-Type

20#0-01-01 - Likely date windowing critical points.
2000-01-(01-M) - M days to 2000, for any special short-term M (30 days, ...).
####-01-01 - N years to/from 2000 - possible problems with N-year subscriptions.
####-##-## - N years to/from your FY 2000 - fiscal year 2000 (Jo Anne effect).
ANY date with a memorable pattern early or late in the 1900's/2000's may have been chosen in the past as a "signal" date.
In fact, any digit or field rollover may fail; I have read of an OS that, at midnight, rolled the last digit of the 9th, 19th, 29th of the month from "9" to "A".
TJD = 0 recurs every ten kilodays from 1968-05-24.

Leaps in Date/Time

Leap Years - Any ####-02-29 and the following ####-03-01 and ####-12-31 (Day 366). Digital watches, etc., may need a 1-day adjustment - check date and day-of-week.
Leap Seconds; Risks Digest 24.02/9.
PC Time Dilation.

Summer Time

Summer Time - BST/DST - Daylight Saving Time :-

Alterations, temporary or permanent, in Rules may cause difficulty or confusion; the US has new Rules from 2007.
Misunderstandings, of Rules may occur; the US 2007 change has been described as "Spring, 3 weeks earlier", which is true in 2007, but only in 3 years out of 7.
Spring :-
- Clocks go forward in EU & NA (and ZA, AU, NZ, etc., ?).
- One hour's worth of civil time is omitted, timed events may be skipped.
- EU-NA time differences change, previously for about a week, but for three or four weeks from 2007; beware auto-changers.
Spring And Autumn :-
- North-South time differences change, perhaps twice.
- Brief time difference changes occur within NA; their zones ripple-change at 0200h clock time, whereas all EU changes simultaneously at 0100h GMT.
- The USA clock change is at 0200h clock time, the UK at 0100h GMT; so do not be surprised if systems change an hour late. My Win98 1st Edn + MSIE 4 changed at 0200h GMT, as was shown by JavaScript Calendars and Clocks.
- See 2001-04-01 - the effect probably repeated, on average, every seven years.
- Dual-boot systems may dual-change.
- Beware possible effects on apparent Windows file timestamps; Risks Digest 22.35/10.
Autumn :-
- Clocks go back in EU & NA (and ZA, AU, NZ, etc., ?).
- One hour's worth of civil time is repeated, timed events may be duplicated. VCRs (Risks Digest 19.43, #11/19), ATMs (ibid. #12/19), birth times (RD 24.92 #9/13), ... can get confused.
- EU-NA time differences change, currently for a few hours.
- AIUI, the first version of Windows 95 (cf. ibid. 13,14/19) sets the clock back whenever it thinks that the clock has reached 2 a.m. on the day in question, not just on the first occasion.
- Reported that some Windows 95 applied out-of-date EU/CET Autumn rules.
UNIX CRON is OK; periodic jobs should not be controlled by local time. Or should they?

Year Rollover

Old DOS GAWK and C Library week numbers - see 2002-12-30 and Batch; affects many years.

Apparently, systems for NASA's shuttles may have inadequate provision for the Year Number to change during flight, so that 2007-01-01 would be 2006-366 - "YERO (Year End Rollover)".

Easter

In some countries, the dates of certain public holidays are governed by that of Easter Sunday. Problems may occur when those coincide with other important dates, such as the beginning or end of a financial year.

Appointments Scheduling

Some "Diary" software is wrongly influenced by Summer Time or Time Zone, using absolute where it should use local, or vice versa. A regular 0900h meeting in Mar-Apr may shift to 0800h. A Londoner, having entered a meeting for 1000h in Paris, may find on arrival that it is now listed as at 1100h. It is unsafe to rely, in today's world, on a time of dubious offset from GMT.

Specific Systems

HMG Red Tape Change Days, April 6 & October 1.
GPS rollover every 1024 weeks, less LeapSecs.
VMS TODR clock needs annual re-basing before 466 days (2^32 × 10 ms) from previous Jan 1st, or next reboot will hiccup. "Information about the VMS TODR (time of day register) problem is in section 20.5.2.1 of the OpenVMS System Manager's Manual".
Windows 98 - any year/day end - The Sunday Times and the BBC report that, at the end of each year, Windows 98 gains two days or loses one. Microsoft agreed saying that this only occurs if Windows 98 is started within a particular but defined second of the last minute of the year; a fix is being developed. See here? But Risks Digest 19.92 #11 says that it can occur any day, if one boots during a critical five seconds near midnight.
Some Microsoft Outlook Calendars have holidays such as US Memorial Day, UK Spring Bank Holiday, UK Late Summer Holiday on the fourth Monday of the month, rather than on the last one as it should be - so being a week early three years in seven. See 1999 above; I only give samples.
Reported that UNIX systems often contain that "Fourth-is-Last" error.
Reported that the Delphi IDE may misjudge file state if the state of Summer Time changes during use. Other IDEs, etc.?

Periodic Events

Critical Periods

In general, these may start, and therefore finish, at any time. They are based on counting in units of time : note that it is not uncommon to count in fractional units, such as tenths of a second.

While not necessarily significantly repetitive, a system with an uninitialised or mis-set calendar or clock may reach a significant moment, Y2k or otherwise, at any time.

Preferred financial periods are likely to be country-dependent - 40-year term loans, 30, 25, 20-year mortgages, etc.

Multiples of Units of Time
Years	Days	hh:mm:ss.sss	Duration	Text	##
-	-	09:06:08	2^15 seconds	Signed WORD wraps	1
-	-	18:12:16	2^16 seconds	Unsigned WORD wraps	2
-	24.85	20:31:23.648	2^31 milliseconds	Signed DWORD wraps	3
-	49.71	17:02:47.296	2^32 milliseconds	Unsigned DWORD wraps	4
-	248.55	13:13:56.480	2^31 centiseconds	Solaris; Galaxy?	5
4.91	1762.0	00:00:00	2^8 weeks	GPS rollover	6
31.90	11650.8	20:16:00	2^24 minutes		7
68.05	-	03:14:08	2^31 seconds	Signed time_t wraps	8
136.10	-	06:28:16	2^32 seconds	Unsigned time_t wraps	9
179.43	65536.0	00:00:00	2^16 days		10

1. -
2. -
3. Windows GetTickCount is a DWORD of milliseconds from boot.
4. Windows GetTickCount. Also used in Internet RFCs.
According to Microsoft, Windows 95/98 could [Q216641] hang; VTDAPI.VXD needs fixing. The problem apparently was fixed in Windows 98 Second Edition and in Windows Millennium. (see Risks Digest 23.53/1,2,3)
5. Report seen : Solaris 2.x hangs when lbolt, which is zeroed at boot and increments every centisecond, flips its MSB. Sun bug ref is 4032974; fixed in 2.6, patches for earlier 2.x.
Also reported - and denied (see Risks Digest 19.93) - that this failure, in the ground controls, killed the Galaxy IV "pager" satellite in May 1998.
6. GPS. See 2003-11-28 above.
7. -
8. -
9. -
10. -

Other Periods

These may be of interest, but are unlikely to be of much technical importance.

8 years : (octaeteris Lunar Cycle) - phases of Moon repeat, approximately - 8×12+3 = 99 lunar months
15 years : Roman Indiction (fiscal)
19 years : (Metonic/Lunar Cycle) - phases of Moon repeat, approximately - 19×12+7 = 235 lunar months
28 years : Julian Calendar (Solar Cycle) - days repeat
50 years : Biblical Jubilee - 7×7+1 or 3×3 + 4×4 + 5×5 years
400 years : Gregorian Calendar - days repeat
532 years : Julian Easter (19×28) - repeats. "Great Paschal Cycle", "Dionysian Cycle", "Victorian Cycle"
2880000 days (20×20×20×18×20) : Mayan Long Count - c. 7885.63 years
7980 years : Julian Period (15×19×28)
49033 years (approx) : Julian/Gregorian seasons match
689472 Hebrew years : Calendar repeats (36288×19)
5700000 years : Gregorian Easter (19×25×30×400) - repeats
39900000 years : Combined Julian & Gregorian Easter?
5255890855047 days = 14390140400 years Gregorian = 14389970112 years Hebrew - Dual Secular (no Easter) calendar repeats ?
74896444684419750 days = 205059500700000 years Gregorian = 205057074096000 years Hebrew - Dual Religious (Easter) calendar repeats ?

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