Table for ADOdb session management Session key to identify a user's browser session. Slightly redundant as it can be dynamically calculated by NOW() and MODIFIED field, but it enables forcing a fixed timeout for specific sessions. New session creation Timestamp. Timestamp which is usually updated when the user interacts with a site, to extend the expire time. Usually a User Id or unique username of your application. The name EXPIREREF is a bit weird, it may be better to call it USERREF? PHP's serialized session data or encrypted serialized session data.