That's not entirely true. you don't have to try to add features in order for the operating environment of a legacy system to change. More users, transaction cou

That's not entirely true. you don't have to try to add features in order for the operating environment of a legacy system to change. More users, transaction count fields overflowing, timestamp fuels hard coated without the century or with 32 bit time_t values... Or it may simply not meet the needs of users anymore. I would hardly hold the air traffic control system up as a model to aspire to, for example. The only reason we run the old one is that the upgrade attempts all failed.