Defines how verbose the output should be. It can be one of
:bug-form, in increasing order of verbosity.
An output stream designator.
A list of conses.
printer-bindings, if supplied, must be a list of conses, where the car of each cons is a symbol. printer-bindings is ignored if keyword is
:quick. Otherwise, around the actual printing it binds each symbol to the value in the cdr of the cons. This is intended to override the bindings that are used in the functions that
output-backtrace should be used by applications in their exception handling routines to log a backtrace whenever an unexpected situation arises. In general, any application that is not intended to be used by Lisp programmers should have error handlers to deal with unexpected situations, and all these handlers should use
LispWorks User Guide and Reference Manual - 20 Sep 2017