[NTG-context] How to put a circle on top of a character

Hi, How can I put a small circle on top of a character in math mode (for the curious this is needed when one defines the interior of a set…). I tried the following, but the small circle is too far away from the character A. I am sure I had an ugly solution for this in plain TeX some years ago but I woul dlike to have an elegant solution in ConTeXt. %%% begin interior-of-a-set.tex \showgrid \starttext \mathtriplet{A}{\circ}{} \startformula \mathtriplet{A}{\circ}{} \stopformula \stoptext %%% end interior-of-a-set.tex Thanks for your help: OK