RE: Temporary notes in Emacs buffers?

[Drew Adams]

> I also considered to implement something like that several times.
> 
> We could use overlays to assign the positions and overlay properties to
> store note texts and metadata.  When a buffer is edited, the overlay
> begin and end marker positions are updated by Emacs on the fly.  I
> would use after-save-hook or so to make Emacs save that stuff 
> automatically for every file save.  Where it is saved would be (file 
> locally) configurable: in a file local variable, in a directory local 
> variable, or in a configurable central place.
> 
> When you open a file, a minor-mode-hook would arrange that everything
> is restored.
> 
> There would also be a variant for dired buffers to attach notes to
> whole files.

FWIW: Marcin said he wasn't interested, but
Bookmark+ really does offer all of that already.

Locations (single position or start+end) of
such "notes" (bookmarks) can be automatically
highlighted.  You can cycle next/previous. You
can hit a key to edit the content (annotation).
Or access any by its name.  (Names can also be
autogenerated.)

[You can also bookmark a multi-region - a set
of zones in a file (or across multiple files).
In that case, you have a single annotation for
the whole set.  (You can have any number of
such sets.)]

Bookmarks are pretty flexible.  You can use
them in lots of different ways.