session_cache_limiter() returns the name of the current cache limiter. If cache_limiter is specified, the name of the current cache limiter is changed to the new value. The cache limiter controls the cache control HTTP headers sent to the client. These headers determine the rules by which the page content may be cached. Setting the cache limiter to nocache, for example, would disallow any client-side caching. A value of public, however, would permit caching. It can also be set to private, which is slightly more restrictive than public. In private mode, the Expire header sent to the client may cause confusion for some browsers, including Mozilla. You can avoid this problem by using private_no_expire mode. The expire header is never sent to the client in this mode. Note: private_no_expire was added in PHP 4.2.0dev.
private_no_expire was added in PHP 4.2.0dev.