Hi Wolfgang,
It is clear, I think I understand (My English is not perfect !). So back to
my original post, if I want only the counter is white and surrounded by a red
frame, just write :

\defineenumeration
  [ex]
   [text=,
    distance=0.3em,
    width=fit,
    numberconversionset=ACCONVERSION,
    alternative=serried,
   ]

\defineprocessor[ACPROCESSOR][command=\ACFRAME]
\defineconversionset[ACCONVERSION][][ACPROCESSOR->n]

Thanks,
Fabrice

2016-07-22 8:08 GMT+02:00 Wolfgang Schuster <schuster.wolfgang@gmail.com>:

> Fabrice Couvreur <fabrice1.couvreur@gmail.com>
> 22. Juli 2016 um 02:02
> Hi Wolfgang,
> In fact, I wanted to know why the instructions to create a new style for
> the counter were useless (% in the code) .
>
> The settings aren’t useless, the are applied to the counter as intended.
>
> \setupbodyfont[pagella,11pt]
>
> \defineprocessor[ACPROCESSOR][color=red]
> \defineconversionset[ACCONVERSION][][ACPROCESSOR->n]
>
> \defineenumeration
>   [ex]
>   [text=,
>    distance=0.3em,
>    width=fit,
>    numberconversionset=ACCONVERSION,
>    alternative=serried]
>
> \starttext
>
> \dorecurse{5}
>   {\startex
>    \input knuth
>    \stopex}
>
> \stoptext
>
> I think I understand that headnumber sends settings (text and number) to
> the \ACFRAME  command.
>
> The headcommand is applied to the text *and* counter of the enumeration
> while numberconversionset
> changes on the counter, i.e. when you want a frame only around the counter
> you have to use
> numberconversionset but when you want a frame around both you have to use
> headcommand.
>
> Wolfgang
>
>
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