dired-mark
dired-mark is an interactive compiled Lisp function in `dired.el
'.
(dired-mark ARG &optional INTERACTIVE)
Mark the file at point in the Dired buffer.
If the region is active, mark all files in the region.
Otherwise, with a prefix arg, mark files on the next ARG lines.
If on a subdir headerline, mark all its files except `.' and `..'.
Use M-x dired-unmark-all-files to remove all marks
and M-x dired-unmark on a subdir to remove the marks in
this subdir.