The US president's birth certificate names him as "Barack Hussein Obama, II". Why does he qualify for the Roman numerals?
When the president released his long-form birth certificate on Wednesday, the focus was on his place of birth, to confirm what most people already knew - he was born in the US.
But it also shone a light on a rarely used part of his name, the II at the end.
The reason for it is, at root, quite simple - the US president has been given his father's name, Barack Hussein Obama. In societies where this is common practice, a method of distinguishing between fathers and sons (and sometimes grandfathers too) is useful.