Just curious about the following result I obtained under ACL4.3 on a
sparcstation running solaris

	USER(22): (setq a '(b c))
	(B C)
	USER(23): (setq d '(e f))
	(E F)
	USER(24): (cdr a . d)

	(C)

It seems to me that it should return an error, which is the case under
CMUCL

	* (setq a '(b c))
	Warning:  Declaring A special.
 
	(B C)
	* (setq d '(e f))
	Warning:  Declaring D special.
 
	(E F)
	* a
 
	(B C)
	* (cdr a . d)
 
	Type-error in KERNEL::OBJECT-NOT-LIST-ERROR-HANDLER:  D is not of type LIST
	 
MCL3.9, which returns
	Error value D is not of expected type LIST

ACL3.0.2 returns an error

	Error: Argument D given to RPLACA or RPLACD should have been a cons in
	ACL::SC-DISPATCH

And Harlequin FreeLisp gives
	Error:Non-list argument D for endp

What's the right thing to do? Does it matter?