[2] Date windowing was one of several techniques used to resolve the year 2000 problem in legacy computer systems.
[3] 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.
This flexibility gave the best of all three major mechanisms: A school could have file RecentDonors set a field named BirthDate to use 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.
[7] The IBM i operating system uses a window of 1940-2039 for date formats with a two-digit year.