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The other common behavior that
Windows users will experience involves dates in spreadsheet programs such as Microsoft Excel, Lotus 1-2-3, and Corel Quattro Pro. If you have typed all your dates with four-digit years (such as 1/1/1999 and 1/1/2000), you should be fine. But if you have typed two-digit
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By defining a pivot year, you direct APPX to determine what century a particular year belongs to. For example, if the pivot year is set to 35, then any date field with a year greater than 35 will be assumed by APPX to have a century value of 19. Any date field with a year less than or equal to the
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Using windowing, programmers instruct software to guess the century for dates that fall within a specific "window" of time, such as the next three decades. The computer interprets the year based on a future so-called hinge date, or pivot, that programmers choose
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A pivot year, also known as date windowing, takes a two-digit year and expands it to determine which century the year is in. Typically the year is converted to either a full four-digit year or into the year-1900 format, as appropriate to the application at
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Those born 2031 are not likely to be donating before 2049, by which time those born 1931 would be 118 years old, and unlikely current donors. DEFCENT and YRTHRESH for a file containing present students and recent graduates would use different values.
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For organizations and institutions with data that is only decades old, a "date windowing" solution was considered easier and more economical than the massive conversions and testing required when converting two-digit years into four-digit years.
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that set the fixed pivot year for the system. Any year after the pivot year will belong to this century (the 21st century), and any year before or equal to the pivot year will belong to last century (the 20th century).
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The choice of the actual pivot year was made by companies based on their historical records. It was in no way an industry standard, nor was this approach in any way professionally recommended. But it would work for a
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Some products, such as
Microsoft Excel 95 used a window of years 1920–2019 which had the potential to encounter a windowing bug reoccurring only 20 years after the year 2000 problem had been addressed.
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operating system uses a window of 1940-2039 for date formats with a two-digit year. In the 7.5 release of the operating system, an option was added to use a window of 1970-2069 instead.
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Closest date: Three different interpretations (last century, this century, and next century) are compared to the current date, and the closest date is chosen from the three.
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The above code establishes a fixed date window of 1960 through 2059. It assumes that none of the receipt dates are before 1960, and should work until
January 1, 2060.
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This flexibility gave the best of all three major mechanisms: A school could have file RecentDonors set a field named BirthDate to use
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is a method by which dates with two-digit years are converted to and from dates with four-digit years. The year at which the
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Below is a simple example of fixed date windowing COBOL code, often used to figure the century for ordinary business dates.
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Sliding pivot year: determined by subtracting some constant from the current year, typically used for birth dates.
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Windowing is a long-term fix that should keep legacy systems working fine until the software is redesigned...
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81:"Century Aware" implementation allowed the user to focus on field-specific and file-specific settings.
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Running software in real time for display and reporting six-digit date into eight-digit date
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years (such as 1/1/29), you may be surprised at the way different programs handle the date.
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of the date window. Date windowing was one of several techniques used to resolve the
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expanded version of the sliding windows technique .. File and field level settings
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Raymond B. Howard. "The Case for
Windowing: Techniques That Buy 60 Years".
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There are three primary methods used to determine the date window:
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Fixed pivot year: simplest to code, works for most business dates.
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pivot year will be assumed by APPX to have a century value of 20.
462:"Announcement Day: IBM Lifts The Veil On IBM i 7.5 And 7.4 TR6"
404:
400:"COMPUTING Spot & fix Y2K problems in Windows 9x & NT"
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DEFCENT=19 YRTHRESH=31, covering those born 1931-2030.
439:"New base year support for 2-digit year date formats"
335:. Information Builders. p. 4. Archived from
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207:"Temporary Y2K fix may last only a generation"
188:, a form of windowing for sequential counters
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245:"The Best of Dates, The Worst Of Dates"
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398:Livingston, Brian (9 February 1999).
7:
300:McNish, Larry (30 December 2019).
14:
243:Healton, Gilbert (12 July 2014).
1:
205:Bridis, Ted (16 March 1999).
302:"The Y2K Pivot Year Problem"
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460:Alex Woodie (3 May 2022).
333:"Solving the Date Dilemma"
186:Serial number arithmetic
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362:"Chapter 1: Pivot Year"
36:legacy computer systems
368:. 2003. Archived from
26:changes is called the
162:environment variables
375:on 22 September 2012
146:RECEIPT-DATE-CENTURY
131:RECEIPT-DATE-CENTURY
75:Information Builders
339:on 27 December 1996
254:on 13 February 2020
366:APPX Software, Inc
331:Kruskopfs, Peter.
308:on 15 January 2020
160:Some systems have
441:. IBM. 3 May 2022
284:Year/2000 Journal
113:RECEIPT-DATE-YEAR
51:Windowing methods
32:year 2000 problem
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419:13 February
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258:13 February
231:arbitrarily
224:13 February
193:References
28:pivot year
466:IT Jungle
42:Reasoning
486:Category
180:See also
101:Examples
343:2 March
24:century
413:(html)
373:(html)
319:while.
252:(html)
218:(html)
149:END-IF
471:4 May
445:4 May
265:hand.
174:IBM i
116:>=
79:FOCUS
70:FOCUS
473:2022
447:2022
421:2020
381:2020
345:2020
314:2020
260:2020
226:2020
172:The
137:MOVE
134:ELSE
122:MOVE
405:CNN
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143:TO
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