\usetypescript[modern][ec]
\setupcolors[state=start]%
\definecolor[clear][y=1,t=0,a=1]%
\setupbodyfont[modern,10pt]
\starttext%
\start%
\setupTABLE[1][1,2,3][aligncharacter=yes,alignmentcharacter={/}]%
\bTABLE%
\bTABLEbody
\bTR%
\bTD{4 \startcolor[clear] 0/8\stopcolor}\eTD%
% the below line works
%\bTD{9 \color[clear] 0/8}\eTD%
\eTR%
\bTR%
\bTD{9 1/8}\eTD%
\eTR%
\bTR%
\bTD{9 1/4}\eTD%
\eTR%
\eTABLEbody%
\eTABLE%
\stop%
\stoptext%
