For the record:
Elias Oltmanns
In the attempt to customise my section headings by means of \setuphead[section][...command=] I followed the instructions at http://wiki.contextgarden.net/Figures_in_Headings#Figures_in_Headings . [...] As it turns out, neither MkII nor MkIV processes the attached example as expected: MkII The table of contents is incomplete, even though the wiki says it shouldn't be;
The solution seems to be to use deeptextcommand instead of textcommand.
MkIV \currentheadnumber seems to be 0 all the time.
Apart from Wolfgang's solution, I have now realised that MkIV allows to use command instead of textcommand / numbercommand and still produces a complete table of contents. Accordingly, the setups look like this: \setuphead[section][command=\Myhead] \def\Myhead#1#2{% Sect #1} Regards, Elias