(document.getElementById) ? dom = true : dom = false;

function hideIt(add){
	if (dom) {document.getElementById('layer'+add).style.visibility='hidden';}
  	if (document.layers) {document.layers["layer"+add].visibility='hide';}
}

function showIt(add){
	if (dom) {
  		if (document.getElementById('layer'+add).style.visibility=='visible'){
  			hideIt(add);
  		}else{
  			document.getElementById('layer'+add).style.visibility='visible'
  		}
	}

	if (document.layers){
  		if (document.layers["layer"+add].visibility=='show'){
  			hideIt(add);
  		}else{
  			document.layers["layer"+add].visibility='show'
  		}
	}
}