"Hmm... it's harder to specify things that way. When somebody's first birthday was is pretty much a fact, but when their most private moment was is a judgment, and probably not one that a lot of people have made, and the people who have might not agree with each other. The guideline that springs to mind is, if you had video footage of your whole life and you handed the pile over to someone who had no idea who you are and a lot of time on their hands, could they find what you're looking for based on that specification? So, 'fifth birthday' would be pretty easy, 'first kiss' would take some looking but probably not a lot of trouble, 'most private moment' would mean they'd have to go through carefully and think about it and might not be able to decide even then."