In particular, the effect of including
in the list value of
is to make all COMMON-LISP symbols be reserved words in respect of definitions and bindings. LispWorks is configured like this because ANSI Common Lisp states that the consequences of such definitions and bindings are undefined. Therefore they are best avoided.
The action taken by LispWorks on such attempted definitions depends on the value of *handle-warn-on-redefinition*.
LispWorks User Guide and Reference Manual - 21 Dec 2011