var layer_state = new Array();
layer_state[0] = 0;
layer_state[1] = 0;
layer_state[2] = 0;


function deactivateOption(activelayer){
			if (document.layers){
		  		document.layers["Layer" + activelayer].visibility="hidden";
			}
			else if (document.all){
				document.all["Layer" + activelayer].style.visibility="hidden";
			}
			else if (document.getElementById) {
				document.getElementById("Layer" + activelayer).style.visibility='hidden';
         		document.getElementById("Layer" + activelayer).style.display='none';
			}
	}


function activateOption(activelayer){
	if (document.layers){
		document.layers["Layer" + activelayer].visibility="visible";
	}
	else if (document.all){
		document.all["Layer" + activelayer].style.visibility="visible";
    }
	else if (document.getElementById) {
		 document.getElementById("Layer" + activelayer).style.visibility='visible';
         document.getElementById("Layer" + activelayer).style.display='block';
	}
}

function ChangeState(layer_id){

if (layer_state[layer_id]==0){
	if (layer_id==0){
		layer_state[1]=0;
		layer_state[2]=0;
	}
	if (layer_id==1){
		layer_state[0]=0;
		layer_state[2]=0;
	}
	if (layer_id==2){
		layer_state[0]=0;
		layer_state[1]=0;
	}
	activateOption(layer_id);
	layer_state[layer_id]=1;
	}
	else {
	deactivateOption(layer_id);
	layer_state[layer_id]=0;
	}
}