function chk_str(str, allow)
{
 var ltrs = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 var len = str.length;
 for(var i = 0; i != len; ++i)
 {
    var ch = str.charAt(i);
    if(ltrs.indexOf(ch) == -1 && allow.indexOf(ch) == -1)
     return false;
 }
 return true;
}

//------------------------------------------------------------------------------

function check_email_address_syntax(addr)
{
 var re = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/;
 return re.test(addr);
}

//------------------------------------------------------------------------------