Seems to me they are defined only on 24.4. iswitchb was marked as obsolete only a few weeks ago. 

-- 
Cheers,
Bozhidar

On December 5, 2013 at 2:46:59 PM, Alex Schroeder (alex@gnu.org) wrote:

Strangely enough the default keybindings you mention (C-j, C-., C-,) are all undefined in my version of Emacs (24.3.1).  

--  
Typed on a tiny keyboard. Sorry for being terse.  

On 05.12.2013, at 03:05, Stefan Monnier <monnier@iro.umontreal.ca> wrote:  

>>> 1. How to pick the first item on the list without typing a lot? I want  
>>> to type a substring RET to pick the most recent buffer. With  
>>> icomplete-mode I type t e s t TAB and get test*.  
>> Why type TAB?  
>  
> Oh, I think I understand. You should hit C-j to select the  
> first item. If you prefer TAB, then do  
>  
> (define-key icomplete-minibuffer-map [?\t]  
> 'minibuffer-force-complete-and-exit)  
>  
>>> 2. How to quickly rotate through the list? I want to type t e s t C-s  
>> C-. and C-, (the logic behind those is that , and . are just below <  
>> and > in the US keyboard).  
>  
> Of course, you can also use C-s and C-r with something like:  
>  
> (define-key icomplete-minibuffer-map [?\C-s]  
> 'icomplete-forward-completions)  
> (define-key icomplete-minibuffer-map [?\C-r]  
> 'icomplete-backward-completions)  
>  
>  
> -- Stefan  
>