A slot description may optionally specify an initial value for the slot. The initial value is the value of the slot in every instance of the class, when the object is first created. The initial value must be a constant of the correct type for the slot.
If an initial value is not specified, a slot is initialized to a value
that depends on its type. All numbers are initialized to 0, of the
appropriate type. Atom and term slots are initialized to the
empty atom
(''). Addresses and pointers are initialized to null pointers. And,
objects are initialized to the null object (see obj-scl-slt-null).
More complicated initialization--not the same constant for every instance of the class--must be performed by create methods, which are described later.