There are two kinds of initarg definitions. \emph{User initargs} are defined
by an explicit @|initarg| item appearing in a class definition: the item
-defines a name, type, and (optionally) a default value for the initarg.
+defines a name, a type, and (optionally) a default value for the initarg.
\emph{Slot initargs} are defined by attaching an @|initarg| property to a
slot or slot initializer item: the property's value determines the initarg's
name, while the type is taken from the underlying slot type; slot initargs do