- <listitem><para>Keeping track of users and sessions, their
- processes and their idle state</para></listitem>
+ <listitem><para>Keeping track of users and sessions, their processes and their idle state. This is implemented by
+ allocating a systemd slice unit for each user below <filename>user.slice</filename>, and a scope unit below it
+ for each concurrent session of a user. Also, a per-user service manager is started as system service instance of
+ <filename>user@.service</filename> for each logged in user.</para></listitem>
+
+ <listitem><para>Generating and managing session IDs. If auditing is available and an audit session ID is already set for
+ a session, then this ID is reused as the session ID. Otherwise, an independent session counter is
+ used.</para></listitem>