I'm developing a custom discussion system for bans, warnings and username changes and would like to know when someone gets unbanned manually. Therefore, I added

{{ /**

• Use this event to perform actions after the unban has been performed
  *
• @event core.acp_unban_after
• @var string mode One of the following: user, ip, email
• @var string user_ids_ary Array with user_ids
• @since
  */
  $vars = array(
  'mode',
  'user_ids_ary',
  );
  extract($phpbb_dispatcher->trigger_event('core.user_unban', compact($vars)));}}

to the end of user_unban() in includes/functions_user.php. I also added a similar event to user_ban().

In phpBB 3.1.5 the events core.acp_ban_after and core.mcp_ban_after are available, but there are no events for unbans.

I prefer adding events for user bans and unbans in includes/functions_user.php above using events in the mcp and acp files. At the locations in functions_user.php more checks and computations have been done. In the case of the user_ban function, I did need the end date of the ban instead of 'ban of 30 minutes'. However, I would be satisfied too if the mcp and acp get events for unbans.