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That would mean you'd have to look for an open bracket inside the url or before the url, to decide how to handle the closing bracket. I've only ever seen this at wikipedia, but it's fairly common there.
I saw it many times on gaming forums, related with stats page, nicks with that kind of symbols at nicks end will be problematic when linking to the forum. Solution is to double place it under bbc url, or the way I like more, to double click on unclickable end of the link and to mark full link and to open in new tab.Examples:http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=^propalica^http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=haywire.http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=god..of..warhttp://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=.t.n.t.http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=[bloodthirst]http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=[wog]ballack.13http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=techni[c4l]http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=undead][roxhttp://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=^k.http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=doiwannaknow..http://dota.eurobattle.net/la/forum/index.php?action=gameinfo;sa=player;sid=1;nick=wearepathetic-Same goes for : then , etcAlso we had many times problems when users used symbols like [ ] and something inside, so some weird things were displayed in topics, but that was easily fixed with insert code.