&optional with &key

[Robert W. Kerns <RWK@SCRC-YUKON.ARPA>]

    Date: Tue 14 May 85 10:05:01-MDT
    From: Robert R. Kessler <KESSLER@UTAH-20.ARPA>

    If you provide an &optional followed by &key's, does that mean that
    the &optional becomes required?  The examples don't seem to address the
    case:

     ((lambda (a &optional (b 3) &key c (d a))
	 (list a b c d x))
      1 :c 7)

    Is this an error (i.e. a is bound to 1, b is bound to :c and 7 causes
    the error), or is a bound to 1, b bound to 3, c to 7 and d to 1.
    -------

It is an error (i.e. A is bound to 1, B is bound to :C and 7 causes
the error).  However, that is not the same as B being required!
All it means is that the keyword arguments start AFTER B.  This
implies that you have to supply B in order to supply C or D, but
that's true in (a &optional (b 3) c (d a)), too.