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This long-term data storage will last 14 billion years
(www.theregister.com)
This is a most excellent place for technology news and articles.
5D is the wrong term, the correct term is multiplex.
It is the correct term if you look at it from a Hilbert space point of view. You have 5 probe options (vector 5D) that give you 5 read options (vector 5D).