On Tue, 6 Aug 2013, Wolfgang Schuster wrote:

>
> Am 06.08.2013 um 16:09 schrieb Alan BRASLAU <alan.braslau@cea.fr>:
>
>> Thank you Wolfgang, but I was wondering about the standard \startnarrower.
>>
>> Many (some) commands allow setup assignments, the use of which overides but does not change the default. This is a very useful feature of ConTeXt that suggest could be generalized. \startnarrower is but one example.
>
> Changing the command is simple but I would drop the second
> argument when you want to change the left/right etc. values
> because you can say “left=4cm” etc. to get the desired margins.

startnarrower has a weird interface. Ideally, it should just support 
keywords:

\startnarrower
     [
       leftmargin=...,
       rightmargin=...,
       alternative=(left|right|both),
       spacebefore=....,
       spaceafter=....,
       indenting=....,
       indentnext=....,
       before=....,
       after=....,
     ]

Aditya