title: Where is the FireBase doc for $other
body: <p>I´m learning FireBase and now at <a href="https://firebase.google.com/docs/database/security/securing-data" rel="nofollow">Using $ Variables to Capture Path Segments</a>
  ' I read about the wildcard usage. I see they use this <code>$other</code>variable.
  Where is a list documentation of all variables that FireBase uses in the RealTime Databas Rules?</p>