About `cl-getf' in CL manual

[Xue Fuqiao]

In the trunk version of (info "(cl) Setf Extensions"):

     Note that for `cl-getf' (as for `nthcdr'), the list argument of
     the function must itself be a valid PLACE form.

What does the "PLACE" form mean here?  Does it mean "generalized
variable"?  I'm confused, because usually only the arguments to a
function being described are in upper case.  Can anybody help?  Thanks.

-- 
Best regards, Xue Fuqiao.
http://www.emacswiki.org/emacs/XueFuqiao