dom = (document.getElementById) ? true : false;
nn4 = (document.layers) ? true : false;
ie = (document.all) ? true : false;
ie4 = ie && !dom;

function changeElem(elemId)
{
if(document.layers)return;
if(dom) 
	if(document.getElementById(elemId).style.display == "block"){
		document.getElementById(elemId).style.display = "none"
	}
	else{
		document.getElementById(elemId).style.display = "block"
	}
else if (ie4) 
	if(document.all[elemId].style.display == "block"){
		document.all[elemId].style.display = "none";
	}
	else{
		document.all[elemId].style.display = "block";
	}
}