function SW() {
    if (location.host=="localhost") document.login.action="/scripts/grades/gr_view.pl";
    if (document.login.username.value=="") {
        alert("Your family name is missing or incorrect!\nPlease use your family name only.");
        document.login.username.focus();
        return(false);
    }
    if (document.login.username.value.indexOf(" ")>=0) {
        alert("Is it your family name?!\nI have found some space characters here.\nPlease use your family name only.");
        document.login.username.focus();
        return(false);
    }
    if (document.login.password.value=="") {
        alert("Your pasword is incorrect or missing!");
        document.login.password.focus();
        return(false);
    }
    return(true);
}