Reading the BGA website I see that there may be some scope for improvement to this page. As far as definitions go, this one seems to be acceptable to common usage. When I look at the rules written it seems slightly incorrect. See http://www.britgo.org/rules/compare.html
Firstly Chinese Rules appear to treat "No Result" as a Draw, Japanese and Korean Rules only are seen to refer to this. The latest Japanese Rules say that When the same whole-board position is repeated during a game, if the players agree, the game ends without result. So the rules do not actually forbid play, do they?
Perhaps the definition could be rejigged a little?
No Result refers an agreed cessation of play by both players, this happens when the position on the board is doomed to repition. A triple ko may cause such a situation to occur. Not same as jigo. Usually specific to Japanese/Korean rules.
Or does this sound rubbish? :)