recentf-file-name-nondir
recentf-file-name-nondir is a compiled Lisp function in `recentf.el
'.
(recentf-file-name-nondir L)
Filter the list of menu-elements L to show filenames sans directory.
This simplified version of `recentf-show-basenames' does not handle
duplicates. It is used by `recentf-arrange-by-dir' as its
`recentf-arrange-by-rule-subfilter'.