lambda-list-keywords
a list, the elements of which are implementation-dependent, but which must contain at least the symbols &allow-other-keys, &aux, &body, &environment, &key, &optional, &rest, and &whole.
5.2.2 27A list of all the lambda list keywords used in the implementation, including the additional ones used only by macro definition forms.
None.
defun, flet, defmacro, macrolet, Section 3.1.2 (The Evaluation Model)
None.