Improving input-methods docs

[Rustom Mody]

Stefan Monnier wrote  (on gnu.emacs.help list):
> Rusi Mody wrote:
> > I see (info "(elisp)input methods")
> > that in emacs including 25, docs are still at
> >
> > | How to define input methods is not yet documented in this manual,
> > | but here we describe how to use them.
> >
> > Is there something I can do (within my capacity!) to move this forward?

> Start to document what you know?  Or try to document what you think
> should be there, and if you don't know what to write because you don't
> know how it works, then ask on emacs-devel.

Ok
First a basic question:
When I do describe-input-method
I see a lot of stuff 'described'
However unlike describe-function|variable etc that links to the relevant stuff
here there is no such.

Is there any way to get to the input method (source) from an activated
input-method?

Strangely even describe-key shows (say) self-insert-command for "\" in
tex-input-method
which seems strange if not plain wrong.
[Yeah I ran grep on the elisp sources and found a quail and an international
and ... Just asking if there is easier way to not get lost]