When past solutions cause future problems [Year 2000 problem]

Currently, a worldwide effort is underway to uncover the calendar-related programs embedded in our legacy software. When these applications were first coded, had programmers rigorously and repeatedly questioned how their code handled date validity, the Year 2000 problem-the largest crisis the information technology industry has yet faced-could have been greatly mitigated. Most code lasts for longer than its original programmers anticipated, and sometimes even outlives successive generations of hardware and operating systems. Not surprisingly, when this legacy code is ported to a new environment, inherited solutions cause new problems. The author suggests several techniques for avoiding or resolving these issues.