// <a href="[URI]" rel="external">にtarget="_blank"と同じ効果を付与
addEvent(window, "load", function(){
	var anchors = document.getElementsByTagName("a");
	for(var i=0; i<anchors.length; i++){
		var a = anchors[i];
		if(a.getAttribute("rel", true) == 'external'){
			a.target = '_blank';
		}
	}
});


// イベント追加
function addEvent(elm,listener,fn){
	try{
		elm.addEventListener(listener,fn,false);
	}catch(e){
		elm.attachEvent("on"+listener,fn);
	}
	return;
}