ANSI Common Lisp 3 Evaluation and Compilation 3.5 Error Checking in Function Calls 3.5.1 Argument Mismatch Detection
188.8.131.52 Invalid Keyword Arguments
It is not permitted to supply a keyword argument to a function
using a name that is not a symbol.
If this situation occurs in a safe call,
an error of type program-error must be signaled
unless keyword argument checking is suppressed as described
in Section 184.108.40.206.1 Suppressing Keyword Argument Checking;
and in an unsafe call the situation has undefined consequences.