Consider the following code:

%\setuphead[section][after={\hairline}]

\starttext

\bTABLE
\bTR \bTD
\section{my section}
\input tufte
\eTD \eTR
\eTABLE

\stoptext

There are two things that are worth mentioning:

1. When compiling with either MkIV or MkII, section number will appear as 3.

2. Uncommenting the setuphead line makes number appear as 4 in MkII, MkIV
doesn't change.

Any ideas?

-- 
Vedran Miletić