Instance Variables

     (object-oriented) Instance variables are the attributes or the data
     portion of an object as defined by the object's class.  Each object,
     when created, is given its own unique set of instance variables
     initialized to their default values.  Instance variables that are
     accessible are called exported instance variables.  Exported instance
     variables can be inspected and--in some cases--assigned using the send
     operator.  The instance variables of an object persist as long as the
     object it belongs to.