The parameter attribute allows you to specify a value that can later be examined. It is returned by the built-in functions parameter or parameter of. This attribute does not affect the appearance of the object.

If you specify a parameter in an object definition, you can then test the value returned by the parameter or parameter of built-in functions, and perform action statements based upon this value. The parameter attribute, when used with the parameter built-in function, is especially useful when specifying actions for individual objects in a class.