function checkRad(name, thisField)
  {
   var j = 0;
   for (var i=thisField.length-1; i > -1; i--)
    {
     if (thisField[i].checked) { j = 1; }
    }
   if (j != 1)
    {
     alert("Please select " + name);
     return false;
    }
   else
     return true;
 }

 function checkSel(name, thisField)
  {
   if (thisField.selectedIndex == 0)
    {
     thisField.focus();
     alert("Please select " + name);
     return false;
    }
   else
     return true;
 }

 function checkLen(name, thisField, minlen)
  {
   if (thisField.value.length < minlen && thisField.value != "  ")
    {
     thisField.focus();
     thisField.select();
     alert("Please enter " + name);
     return false;
    }
   else
     return true;
  }

function checkNumChecked(name,thisField,min,max)
 {
  var num = 0;
  for (i = 0; i < thisField.length;  i++)
   {
    if (thisField[i].checked)
     { num++; }
   }
  if (num < min && min > 0)
   {
    alert ("You must select at least " + min + " " + name + " options");
    return false;
   }
  else
    if (num > max && max > 0)
     {
      alert ("Please limit your " + name + " selections to " + min + " - " + max + " options");
      return false;
     }
    else
      return true;
 }

function emailCheck (emailStr) 
 {
  /* The following variable tells the rest of the function whether or not to verify that the address ends in a two-letter country 
     or well-known TLD.  1 means check it, 0 means don't. */

  var checkTLD=1;

  // The following is the list of known TLDs that an e-mail address must end with.

  var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;

  /* The following pattern is used to check if the entered e-mail address fits the user@domain format.  It also is used to 
     separate the username from the domain. */

  var emailPat=/^(.+)@(.+)$/;

  /* The following string represents the pattern for matching all special characters.  We don't want to allow special
     characters in the address.  These characters include ( ) < > @ , ; : \ " . [ ] */

  var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";

  /* The following string represents the range of characters allowed in a username or domainname.  It really states 
     which chars aren't allowed.*/

  var validChars="\[^\\s" + specialChars + "\]";

  /* The following pattern applies if the "user" is a quoted string (in which case, there are no rules about which 
     characters are allowed and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com is a legal e-mail address. */

  var quotedUser="(\"[^\"]*\")";

  /* The following pattern applies for domains that are IP addresses, rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal
      e-mail address. NOTE: The square brackets are required. */

  var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;

  // The following string represents an atom (basically a series of non-special characters.)

  var atom=validChars + '+';

  /* The following string represents one word in the typical username.  For example, in john.doe@somewhere.com, john and doe are words.
     Basically, a word is either an atom or quoted string. */

  var word="(" + atom + "|" + quotedUser + ")";

  // The following pattern describes the structure of the user

  var userPat=new RegExp("^" + word + "(\\." + word + ")*$");

  // The following pattern describes the structure of a normal symbolic domain, as opposed to ipDomainPat, shown above.

  var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");

  /* Finally, let's start trying to figure out if the supplied address is valid. */
  /* Begin with the coarse pattern to simply break up user@domain into different pieces that are easy to analyze. */


  // Too many/few @'s or something; basically, this address doesn't even fit the general mould of a valid e-mail address.
  var matchArray=emailStr.match(emailPat);
  if (matchArray==null) 
   {
    alert("Email address seems incorrect (check @ and .'s)");
    return false;
   }

  var user=matchArray[1];
  var domain=matchArray[2];

  // Start by checking that only basic ASCII characters are in the strings (0-127).
  for (i=0; i<user.length; i++)
   { 
    if (user.charCodeAt(i)>127) 
     {
      alert("Ths username contains invalid characters.");
      return false;
     }
   }
  for (i=0; i<domain.length; i++) 
   {
    if (domain.charCodeAt(i)>127) 
     {
      alert("Ths domain name contains invalid characters.");
      return false;
     }
   }

  // See if "user" is valid 

  if (user.match(userPat)==null) 
   {
    alert("The username doesn't seem to be valid.");
    return false;
   }

  // if the e-mail address is at an IP address (as opposed to a symbolic host name) make sure the IP address is valid.

  var IPArray=domain.match(ipDomainPat);
  if (IPArray!=null) 
   {
    // this is an IP address
    for (var i=1;i<=4;i++) 
     {
      if (IPArray[i]>255) 
       {
        alert("Destination IP address is invalid!");
        return false;
       }
     } 
    return true;
   }

// Domain is symbolic name.  Check if it's valid.
 
   var atomPat=new RegExp("^" + atom + "$");
   var domArr=domain.split(".");
   var len=domArr.length;
   for (i=0;i<len;i++) 
    {
     if (domArr[i].search(atomPat)==-1) 
      {
       alert("The domain name does not seem to be valid.");
       return false;
      }
    }

   /* domain name seems valid, but now make sure that it ends in a known top-level domain (like com, edu, gov) or a two-letter word,
      representing country (uk, nl), and that there's a hostname preceding the domain or country. */

   if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) 
    {
     alert("The address must end in a well-known domain or two letter " + "country.");
     return false;
    }

// Make sure there's a host name preceding the domain.

   if (len<2) 
    {
     alert("This address is missing a hostname!");
     return false;
    }
   
    // If we've gotten this far, everything's valid!
    return true;
   }