function swap(obj,iState){
	var strFilename = obj.firstChild.src;
	var strRE;
	if (iState == 1) {
		strRE = /_0/g;             //Create regular expression pattern.
	}else{
		strRE = /_1/g;
	}
	strTemp = strFilename.replace(strRE, "_" + iState);
	obj.firstChild.src = strTemp;    //Replace "_0" with "_1" and vice-versa
}