I can get more anal than that: cogs are just the teeth on the gear, so technically bikes don't actually have gears (unless it is shaft-driven), but a series of sprockets that can be switched to achieve gearing. At this point I realise I am disappearing up my own arse but hey
Velosolo also ahead of you on that one: http://www.velosolo.co.uk/faq.html#d20