Am 11.06.2013 um 15:53 schrieb Jan Pohanka <xhpohanka@gmail.com>:

> 
>> \definesectionalternative[mysection][renderingsetup=mysection]
>> 
>> \startsetups[mysection]
>>   \vbox\bgroup
>>     \headsetupspacing
>>     \strut\headnumbercontent\par
>>     \begstrut\headtextcontent\endstrut
>>   \egroup
>> \stopsetups
>> 
>> \setuplabeltext[en][section={}{Section]
>> 
>> \setuphead[section][alternative=mysection]
>> 
>> 
> It seams that my context does not know definesectionalternative


Has to be \defineheadalternative:

\defineheadalternative[mysection][renderingsetup=mysection]

\startsetups[mysection]
  \vbox\bgroup
    \headsetupspacing
    \strut\headnumbercontent\par
    \begstrut\headtextcontent\endstrut
  \egroup
\stopsetups

\setuplabeltext[en][section={, Section}]

\setuphead
  [section]
  [alternative=mysection,
   conversion=I,
   sectionstopper=.]

\starttext 
\section{Test}
\stoptext

Wolfgang