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.
3.4.1.4.1.1 Examples of Suppressing Keyword Argument Checking