Hi Wolfgang,
thank you for the answer (There is much to know !).

I would also have this:
>
> I First chapter
>    Activity
>    1.1 Second section
>    1.2 Third section


\setupheadnumber[section][0]

Fabrice

2016-07-13 18:20 GMT+02:00 Wolfgang Schuster <schuster.wolfgang@gmail.com>:

> Fabrice Couvreur <fabrice1.couvreur@gmail.com>
> 13. Juli 2016 um 17:09
> Hello,
> I wish that in the table of contents and only one, the number of chapters
> are I, II, III, IV ...
>
> When you change a different conversion for the chapter numbers only in the
> ToC use this:
>
> \defineconversionset[chapterconversion][n,R][n]
>
>     \setuplist
>         [chapter]
>         [numberconversionset=chapterconversion]
>
> but when you want it in the entire document use this:
>
> \defineconversionset[chapterconversion][n,R][n]
>
>     \setuphead
>         [chapter]
>         [sectionconversionset=chapterconversion]
>
> Wolfgang
>
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to
> the Wiki!
>
> maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
>
> ___________________________________________________________________________________
>