Returning additional values from advertised functions

[David A. Moon <Moon@SCRC-STONY-BROOK.ARPA>]

    Date: Thu 19 Sep 85 19:27:24-EDT
    From: Richard Mlynarik
    I have been inconvenienced several times recently by the fact the
    multiple-value-setq is not multiple-value-setf.  This is a somewhat
    curious shortcoming, especially now that the All-New Fashion in lisp
    code seems to be to entirely eschew setq in favour of setf.

(multiple-value-setq (a b c) (foo))
and
(setf (values a b c) (foo))
are identical, and the latter allows you to put the values into other
places besides variables.  The latter form is not standard Common Lisp,
but it should be.