I tried to put the sectionnumbers in the margin, but it didn't work. The I looked at the example in the ConTeXt Reference Manual and this didn't work either. Why?
See the minimal example below where the manual is contrasted with the actual output.

Hans van der Meer

\setuppapersize[A5][A5]
\starttext
\startchapter[title=Test]
>From ConTeXt Reference Manual 18 october 2012 page 210\crlf
\externalfigure[headers.jpg][width=0.8\textwidth]
\startsection[title=enclosing section]
\setupheads[alternative=normal]
\subsection{Title alternative equals normal}
\setupheads[alternative=inmargin]
\subsection{Title alternative equals inmargin}
\setupheads[alternative=middle]
\subsubject{Title alternative equals middle}
\stopsection
ConTeXt  ver: 2013.03.20 10:34 MKIV  fmt: 2013.3.20
\stopchapter
\stoptext