-- Same with passwords.
user_email tinytext NOT NULL,
- -- This is a timestamp which is updated when a user
- -- logs in, logs out, changes preferences, or performs
- -- some other action requiring HTML cache invalidation
- -- to ensure that the UI is updated.
+ -- If the browser sends an If-Modified-Since header, a 304 response is
+ -- suppressed if the value in this field for the current user is later than
+ -- the value in the IMS header. That is, this field is an invalidation timestamp
+ -- for the browser cache of logged-in users. Among other things, it is used
+ -- to prevent pages generated for a previously logged in user from being
+ -- displayed after a session expiry followed by a fresh login.
user_touched binary(14) NOT NULL default '',
-- A pseudorandomly generated value that is stored in