var READY_STATE_UNINITIALIZED=0;
var READY_STATE_LOADING=1;
var READY_STATE_LOADED=2;
var READY_STATE_INTERACTIVE=3;
var READY_STATE_COMPLETE=4;

function inicializa_xhr() {
	if(window.XMLHttpRequest) {
		return new XMLHttpRequest();
	}
	else if(window.ActiveXObject) {
		return new ActiveXObject("Microsoft.XMLHTTP");
	}
}