function popUp(URL) {
id = "allthesame";
eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=1,location=0,statusbar=0,menubar=0,resizable=1,width=570,height=470,left=20,top=40');");
}

/* id is the window title. By giving it a fixed name as above, each popup will replace a previously opened popup. Conversely, the time-derived id below will make each popup open in a new window */

/*
function popUp(URL) {
day = new Date();
id = day.getTime();
eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=1,location=0,statusbar=0,menubar=0,resizable=1,width=370,height=250,left=50,top=155');");
}
*/