wxm = 590;
wym = 420;
x = (screen.width  - wxm) / 2;
y = (screen.height - wym) / 2;

function wop01() {window.open("a4_idemni.html","win1","left="+x+",top="+y+",menubar=no,toolbar=no,location=no,directories=no,status=yes,scrollbars=yes,width="+wxm+",height="+wym);}