var AA = new Array;
AA[0] = new Option('所有子类','AA');
var ZZ = new Array;
ZZ[0] = new Option('请先选种类','ZZ');
var AL = new Array;
AL[0] = new Option('所有子类','AA');
AL[1] = new Option('电子屏','L');
AL[2] = new Option('三面翻','T');
var BB = new Array;
BB[0] = new Option('所有子类','AA');
BB[1] = new Option('跨街广告牌','A');
BB[2] = new Option('桥体广告牌','B');
BB[3] = new Option('霓虹灯广告牌','N');
BB[4] = new Option('墙顶广告牌','R');
BB[5] = new Option('立地广告牌','S');
BB[6] = new Option('单立柱','U');
BB[7] = new Option('楼体广告牌','W');
var ST = new Array;
ST[0] = new Option('所有子类','AA');
ST[1] = new Option('候车亭灯箱','B');
ST[2] = new Option('自行车棚护栏灯箱','C');
ST[3] = new Option('交通护栏灯箱','F');
ST[4] = new Option('悬挂式灯箱','H');
ST[5] = new Option('资讯亭灯箱','I');
ST[6] = new Option('街道立地灯箱','L');
ST[7] = new Option('阅报栏灯箱','N');
ST[8] = new Option('小单立柱','O');
ST[9] = new Option('电话亭灯箱','P');
ST[10] = new Option('地名牌灯箱','S');
var TR = new Array;
TR[0] = new Option('所有子类','AA');
TR[1] = new Option('机场内媒体','A');
TR[2] = new Option('车身广告','B');
TR[3] = new Option('车内广告','I');
TR[4] = new Option('地铁广告','M');
TR[5] = new Option('火车内媒体','T');
var obj
function chSubType(obj)
{
	with (obj)
	{
		var selectedValue = media_type.options[media_type.selectedIndex].value
		eval("var leng = "+selectedValue+".length");
        
		for (var i=40;i>0;i--)
		{
			media_subtype.options[i] = null;
		}
		
		for (var i=0;i<leng;i++)
		{
			eval("media_subtype.options[i] = "+selectedValue+"[i]");
		}
	}
}

function rmvShowAllOption(obj)
{
	obj.media_subtype.options[0] = null;
}