My answer to the last question would probably be including a reader right with it. AC current will likely be around a lot longer than 50 years. So if you have s

My answer to the last question would probably be including a reader right with it. AC current will likely be around a lot longer than 50 years. So if you have some kind of computer containing the data, just need to plug it in and it starts a self-explaining film(ideally with pictogrammes, several language explanations, etc) that should make the data usable...