Losing form data when clicking the back button on browser [duplicate]

Answer 1

This applies to PHP and IE8.

Not only must you set cacheing to private, but you must remove the 4 cacheing headers and this can only be done with PHP 5.3.

In PHP 5.2 you can only set the 4 headers to blank values if using the Zend Framework's setHeader() method. For some reason is not sufficient on IE8 to set the 4 header values to empty values. Here's the code for PHP 5.3:

header_remove("Expires"); 
header_remove("Cache-Control"); 
header_remove("Pragma"); 
header_remove("Last-Modified");