To convert the dates is one thing. To make sure that the repaired dates in your system coincide with the repair dates in the systems you interact with is something else.
The Central Intelligence Agency has this problem in a big way. It shares data with its Crime and Narcotics Center and the Counter Terrorism Center. The problem is, the U.S. Government refuses to set a date standard for all of its agencies.
Another problem the CIA faces is that it is way behind. As of March, 1997, it was still shopping for consulting firms and evaluating tools it can use to conduct impact analysis and generate code repairs.
The CIA says it will complete its repairs in 1997. It is the most optimistic of all U.S. Government agencies.