function getPlatform()
    {
      if (navigator.platform.indexOf("Win32") != -1)
        return "Windows";
      else if (navigator.platform.indexOf("Linux") != -1)
        return "Linux";
      else if (navigator.userAgent.indexOf("Mac OS X") != -1)
        return "MacOSX";
      else if (navigator.userAgent.indexOf("MSIE 5.2") != -1)
        return "MacOSX";
      else if (navigator.platform.indexOf("Mac") != -1)
        return "Mac";
      return "Other";
    }


function checkform(aform) {
		
	if (isempty(aform.txt_first.value)) 
	{
		err = "Please enter your first name. \n";
	}
	else if (isempty(aform.txt_last.value)) 
	{
		err = "Please enter your last name. \n";
	}
	else if (!validateEmail(aform.txt_email.value,1,0))
	{
		err = "Please enter a valid email address. \n";
	}
	else if (isempty(aform.img_key.value))
	{
		err = "Please enter the image key in the correct field. \n";
	}
	else
	{
		err= "";
	}
	
	if (err.length != "")
	{	
		alert(err);
		return false;
	}
	
	aform.submit();
	return true;
	
}

function isempty(field) {
	if (field.length <= 2) {
		return true;
	}
}

function ichar(field) {
	var ichars = "~#\\\|/=+{}\'\"<>?:";
	
	for (var i = 0; i < field.value.length; ++i) {
		if (ichar.indexof(field.value.charAt(i)) != -1) {
			alert ("Please remove special characters. \n These are not allowed.\n");
			return false;
		}
	}
}

function validateEmail(addr,man,db) {
if (addr == '' && man) {
   if (db) alert('email address is mandatory');
   return false;
}
var invalidChars = '\/\'\\ ";:?!()[]\{\}^|';
for (i=0; i<invalidChars.length; i++) {
   if (addr.indexOf(invalidChars.charAt(i),0) > -1) {
      if (db) alert('email address contains invalid characters');
      return false;
   }
}
for (i=0; i<addr.length; i++) {
   if (addr.charCodeAt(i)>127) {
      if (db) alert("email address contains non ascii characters.");
      return false;
   }
}

var atPos = addr.indexOf('@',0);
if (atPos == -1) {
   if (db) alert('email address must contain an @');
   return false;
}
if (atPos == 0) {
   if (db) alert('email address must not start with @');
   return false;
}
if (addr.indexOf('@', atPos + 1) > - 1) {
   if (db) alert('email address must contain only one @');
   return false;
}
if (addr.indexOf('.', atPos) == -1) {
   if (db) alert('email address must contain a period in the domain name');
   return false;
}
if (addr.indexOf('@.',0) != -1) {
   if (db) alert('period must not immediately follow @ in email address');
   return false;
}
if (addr.indexOf('.@',0) != -1){
   if (db) alert('period must not immediately precede @ in email address');
   return false;
}
if (addr.indexOf('..',0) != -1) {
   if (db) alert('two periods must not be adjacent in email address');
   return false;
}
var suffix = addr.substring(addr.lastIndexOf('.')+1);
if (suffix.length != 2 && suffix != 'com' && suffix != 'net' && suffix != 'org' && suffix != 'edu' && suffix != 'int' && suffix != 'mil' && suffix != 'gov' & suffix != 'arpa' && suffix != 'biz' && suffix != 'aero' && suffix != 'name' && suffix != 'coop' && suffix != 'info' && suffix != 'pro' && suffix != 'museum') {
   if (db) alert('invalid primary domain in email address');
   return false;
}
return true;
}