Dired: how to mark with other character but *

[Jean Louis]

I would like to use this specific workflow in Dired like following:

- I am reviewing videos, so I have to use in Dired either ! or & to
  review a video

- I wish to mark specific videos for later referencing

- if I mark it with `m' then the next invocation of ! or & will
  operate on marked files. Right now I am memorizing which videos are
  to be marked, and not use Emacs to help me

- if ! operates only on files marked as * then I could as a solution
  mark files with some other character, let us say V but I wish to
  know how to do it

- Later, those files marked with V character I could replace to *
  character to operate on such videos, that I know how to do from the
  manual

What I do not find in the manual is how to mark files with some other
character. That is what would make my above envisioned workflow
useful.

Jean