function Is(){
	this.ie4=document.all;
	this.ns4=document.layers;
	this.w3c=document.getElementById;
	this.ns6=document.getElementById&&!document.all;
}
var is=new Is();
if (is.w3c|is.ns4|is.ns6) this.doc = document
else if (is.ie4) this.doc = document.all