An important part of making a database Y2K compliant is to always include the century as part of a date. Otherwise the exact value of date is left up to interpretation. For example does the date 7/22/99 really mean 7/22/1999 or 7/22/2099?
4th Dimension has a date format and a date entry filter that are especially useful for making sure your database is Y2K compliant. The entry filter to use for date entry is !0&9##/##/####. It forces the user to enter the century as part of the date. If the user has not entered the century in a date, the date will be considered invalid and not accepted.
4D 6.0.5 introduced the "mm/dd/yyyy Forced" date format. This format always displays a date with the century. This is important because other date formats will only display the date if the operating system is set to display the century.
An example defining the date format and entry filter that contain the century.