Share 'Caffeine and theobromine'

I've read that chocolate may not even have caffeine in it after all but only similar stimulants, one of which is theobromine. What do you think? Can anyone point to a definitive answer to this? A related question-- I've seen lists of how much caffeine is in dark chocolate. How do they measure that, and doesn't the amount of stimulant vary with the cacao percentage? Surely a 100% bar of 100g has…