3.4.1.5 Suppressing Keyword Argument Checking

If &allow-other-keys was specified in the lambda list of a function, keyword_2 argument checking is suppressed in calls to that function.

If the :allow-other-keys argument is true in a call to a function, keyword_2 argument checking is suppressed in that call.

The :allow-other-keys argument is permissible in all situations involving keyword_2 arguments, even when its associated value is false.