&optional with &key

[Guy Steele <gls@AQUINAS.ARPA>]

It isn't quite accurate to say that the presence of &key makes an
&optional parameter be required.  It is true, however, that, if a
function has both &optional and &key parameters, it is impossible to
specify explicit arguments for any keyword parameters unless arguments
are first explicitly given for all optional parameters.  The book
doesn't say so in one sentence, but you can deduce this from careful
reading of page 61.  I agree that an explicit statement of this fact
would be worthwhile, and that an example would be useful.
--Guy