Some was developed in-house, some by consultants, some by employees who have long since left the Agency. Most can be converted to new products with varying degrees of difficulty. If a development environment or database has a formal date format, use it. When creating a custom date format with a programming language, development tool, or database, use a date format that captures more than the last two digits of a year and include testing to ensure a smooth transition into the next century. Custom-built application software especially if it was developed for one company's use.
Similar problems exist with many other programs from many other vendors.
Beware when performing long-term calculations. The system date must be manually set to the year 2000. Once set it is compliant. This will be an annoyance and can be taken care of on the first working day of the new century. The system has a flash ROM BIOS that needs to be upgraded with a utility in order to be compliant.