function popUp(URL,zab,luz){
	lehZabal=screen.width;
	lehLuz=screen.height;
	ezkPos=(lehZabal-zab)/2;
	goiPos=(lehLuz-luz)/2;
	window.open(URL,"ventana","left="+ezkPos+", top="+goiPos+", width="+zab+", height="+luz+", scrollbars=1, menubar=no, location=no, resizable=no");
}