Year 2000 problem
The Year 2000 problem (also known as the Y2K problem, the Millennium bug, the Y2K bug, or simply Y2K) was a problem for both digital (computer-related) and non-digital documentation and data storage situations that resulted from the practice of truncating a four-digit year to two digits. This made year 2000 indistinguishable from 1900. The former assumption that a twentieth-century date was always understood caused various errors concerning, in particular, the display of dates and the automated ordering of dated records or real-time events.
In 1997, the British Standards Institute (BSI) developed a standard, DISC PD2000-1, which defines "Year 2000 Conformity requirements" as four rules:
No valid date will cause any interruption in operations.
Calculation of durations between, or the sequence of, pairs of dates will be correct whether any dates are in different centuries.
In all interfaces and in all storage, the century must be unambiguous, either specified, or calculable by algorithm.
