var selectedValue = -1;

function Validate_String(string, return_invalid_chars)
{
valid_chars = '1234567890-_.^~abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
invalid_chars = '';

if(string == null || string == '')
  return(true);

//For every character on the string.   
for(index = 0; index < string.length; index++)
  {
  char = string.substr(index, 1);                        
  
  //Is it a valid character?
  if(valid_chars.indexOf(char) == -1)
    {
    //If not, is it already on the list of invalid characters?
    if(invalid_chars.indexOf(char) == -1)
      {
      //If it's not, add it.
      if(invalid_chars == '')
         invalid_chars += char;
      else
         invalid_chars += ', ' + char;
      }
    }
  }                     
  
//If the string does not contain invalid characters, the function will return true.
//If it does, it will either return false or a list of the invalid characters used
//in the string, depending on the value of the second parameter.
if(return_invalid_chars == true && invalid_chars != '')
 {
 last_comma = invalid_chars.lastIndexOf(',');
 
 if(last_comma != -1)
    invalid_chars = invalid_chars.substr(0, $last_comma) + 
    ' and ' + invalid_chars.substr(last_comma + 1, invalid_chars.length);
            
 return(invalid_chars);
 }
else
 return(invalid_chars == ''); 
}

function Validate_Email_Address(email_address)
 {
 //Assumes that valid email addresses consist of user_name@domain.tld
 at = email_address.indexOf('@');
 dot = email_address.lastIndexOf('.');
 
 if(at == -1 || 
    dot == -1 || 
    dot <= at + 1 ||
    dot == 0 || 
    dot == email_address.length - 1)
    return(false);
    
 user_name = email_address.substr(0, at);
 domain_name = email_address.substr(at + 1, email_address.length);                  
 
 if(Validate_String(user_name) === false || 
    Validate_String(domain_name) === false)
    return(false);                     
 
 return(true);
 }

function ValidateSubmit()
{
 if(("" + frm.FirstName.value).replace(/\ /g,"") == "")
 {
 	alert("Please specify your first name.");
	return false;
 }
 if(("" + frm.LastName.value).replace(/\ /g,"") == "")
 {
 	alert("Please specify your last name.");
	return false;
 }
 if(frm.Country.value == "")
 {
 	alert("Please specify your country of residence.");
	return false;
 }
 if(!Validate_Email_Address(frm.Email.value))
 {
  alert("Please specify a valid email address.");
  return false;
 }
 if(frm.TelephoneCode.value == "")
 {
 	alert("Please specify the international access code for your phone number.");
  return false;
 }
 if(("" + frm.TelephoneNumber.value).replace(/\ /g,"") == "")
 {
 	alert("Please specify your phone number.");
  return false;
 }
 
 if(!frm.AcceptTac.checked)
 {
  alert("In order for us to send you the requested data you must allow us to contact you.");
  return false;
 }
 
 frm.cmdOk.disabled = true;
 
 return true;
}