Cache-Control: no-cache and browser back button problem

why does the cache control header generated by php (under session_cache_limiter = nocache) needs to have no-store? It makes pressing Back in the browser requests a new version of the page (which is unwanted in some situations, e.g. while filling form and needs to edit a few fields before re-submitting). Also, when I am editing the script and had a fatal error (like a PHP syntax error), the stored version of the page by the browser is always the one with a fatal error, and I need to always refresh to get the current version (I am using a 'Never check for newer versions of pages' in my browser, which is fine for most circumstances). Can I remove the 'no-store' parameter from the generated Cache-Control header, without resorting to session_cache_limiter = private (since this also have some Refresh problems in IE)? -- sh