The nature and format of the printed information is implementation-dependent. However, implementations are encouraged to provide such information as elapsed real time, machine run time, storage management statistics, and so on. For instance, describe of a symbol will exhibit the symbol's value, its definition, and each of its properties. The nature and format of the output is implementation-dependent. Each implementation must provide a method on the class standard-object and methods on enough other classes to ensure that there is always an applicable method.
Implementations are free to add methods for other classes.
The first argument may be any Lisp object. The values returned by describe-object are unspecified. Methods on describe-object may recursively call describe . Indentation, depth limits, and circularity detection are all taken care of automatically, provided that each method handles exactly one level of structure and calls describe recursively if there are more structural levels. If this rule is not obeyed, the results are undefined.