Changes

\useMPlibrary [dum] %% sample images\starttext \startplacefigure [location=none] %\startsubfloatnumbering % This does not work! \startfloatcombination [nx=2, ny=1] \startplacefigure [title=Left, reference=figref:left, group=one, groupsuffix=a] \externalfigure \stopplacefigure \startplacefigure [title=Right, reference=figref:right, group=one, groupsuffix=b] \externalfigure \stopplacefigure

%\stopsubfloatnumbering % This does not work! \stopplacefigure

See \in{figureimage}[figref:leftright] (right) and \in{figureimage}[figref:rightleft](left).\stoptext