function validate_required(field,alerttxt)
{
    with (field){
        if (value==null||value=="")
        {alert(alerttxt);return false;}
        else {return true;}
    }
}
function validate_select(field,alerttxt)
{
    if (field.selectedIndex == 0)
    {alert(alerttxt);return false;}
    else {return true;}
}
function validate_email(field,alerttxt)
{
    with (field) {
        apos=value.indexOf("@")
        dotpos=value.lastIndexOf(".")
        if (apos<1||dotpos-apos<2)
        {alert(alerttxt);return false;}
        else {return true;}
    }
}