ANSI Common Lisp 19 Filenames 19.1 Overview of Filenames 19.1.2
Pathnames as FilenamesPathnames are structured objects that can
represent, in an implementation-independent way, the filenames
that are used natively by an underlying file system. A pathname
need not correspond to any file that actually exists, and more
than one pathname can refer to the same file. For example, the
pathname with a version of :newest might refer to the same file
as a pathname with the same components except a certain number
as the version. Indeed, a pathname with version :newest might
refer to different files as time passes, because the meaning of
such a pathname depends on the state of the file system. Some
file systems naturally use a structural model for their
filenames, while others do not. Within the Common Lisp pathname
model, all filenames are seen as having a particular structure,
even if that structure is not reflected in the underlying file
system. The nature of the mapping between structure imposed by
pathnames and the