[marshray]

OK, so it's only a prison to the extent you use it.

Better not let your important data get locked up in any non-portable formats though. A literal prison is far easier to release someone from.

[srdev]

It's not a prison even if you do use it. The defining characteristic of a prison is that you cannot leave it. I can stop using an iPad any time I wish.

And yes, important data should not be locked in non-portable formats. At the same time, I've never found myself in a situation where I simply could not extract important data from a non-portable format into a more portable one.