I'd be surprised if the specs were simply lost. More likely, they said, "Load <archaic file format> into <obsolete software> on the <ancient machine you'd have

I'd be surprised if the specs were simply lost. More likely, they said, "Load <archaic file format> into <obsolete software> on the <ancient machine you'd have to get from a computing history museum> to control <manufacturing process nobody uses anymore>." And after fiddling with the design for a while, someone said, "Well, we can approximate that with <modern manufacturing process>, but the <technical characteristic> is going to be 10 instead of 5. Is that okay?" And there was nobody around who knew.