The 'n=' option to \setupnote doesn't have any effect, more ever 'n=0'
will give an "Arithmetic overflow" error. Minimal example:

\setupnote[footnote][n=0]

\starttext
This\footnote{one} and this\footnote{two} and this\footnote{three}.
\stoptext

Regards,
 Khaled


-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer