title: Protected static member variables
body: <p>I've recently been working on some class files and I've noticed that the member variables had been set in a protected static mode like protected static $_someVar and accessed like static::$_someVar.</p>
  
  <p>I understand the concept of visibility and that having something set as protected static will ensure the member variable can only be accessed in the super class or derived classes but can I access protected static variables only in static methods?</p>
  
  <p>Thanks</p>