if (document.images) {
	var imgNames = new Array("s_lt","b_lt","s_mt","b_mt","s_rt","b_rt","s_lm","b_lm","s_mm","b_mm","s_rm","b_rm","s_lb","b_lb","s_mb","b_mb","s_rb","b_rb");
	var matrix = new Array(18);
	for (var i = 0; i <18; i++) {
		matrix[imgNames[i]] = new Image();
		matrix[imgNames[i]].src = "./images/" + imgNames[i] + ".gif";
	}
}

function chgImg(id,name) {
	if (document.images) {
		document.images[id].src = matrix[name].src;
	}
}