Namestrings always use local file system case conventions, but Common Lisp functions that manipulate pathname components allow the caller to select either of two conventions for representing case in component values by supplying a value for the :case keyword argument. The next figure lists the functions relating to pathnames that permit a :case argument:
Figure 19-2. Pathname functions using a :CASE argument
make-pathname pathname-directory pathname-name
pathname-device pathname-host pathname-type
19.2.2.1.2.1 Local Case in Pathname Components
19.2.2.1.2.2 Common Case in Pathname Components