On Tue, 5 Jul 2016, Kaushal Modi wrote:

> In this commit ( http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=08974112ae68aefba658a8516c8faa3374edc924 ), I am wondering
> why we have two bindings "%c" and "%g" call the same command?
> Why not have just one binding? That way, the user's get used to the same binding; we won't have a split where some prefer %c and
> some prefer %g. Then there are no bad feelings when/if one of the bindings might need to be sacrificed in future for some reason.
It was a compromise solution:
I)

My preference is '%g', which is the same as 
`dired-mark-files-containing-regexp'.
That is consistent with the design of Ibuffer, as stated in the
first line of ibuffer.el:
;;; ibuffer.el --- operate on buffers like dired

There are several equivalent commands Dired-Ibuffer with the same
key bindings, for instance:
dired-mark-directories
ibuffer-mark-dired-buffers
both are bound to '*/'

That very much helps to remember then.

Unfortunatelly, this symmetry Dired-Ibuffer is not perfect:
there are Ibuffer commands with the Dired 'partner' having
a different binding. For instance:
`dired-mark-files-regexp' bound to '%m'
`ibuffer-mark-by-name-regexp' bound to '%n'.

II)
Ibuffer has the command:
`ibuffer-filter-by-content' bound to '/c'

So i think one Ibuffer user may find easier to remember the
binding '%c' for `ibuffer-mark-by-content-regexp'.

If people agree to keep just one binding then i would suggest '%g'.
Regards,
Tino