\stopplaceformula
% numbered formula with list text, note without a reference option the formula is just a placeformula that is not listed in the list of formulas -- needs ConTeXt latest version 2021-03-20 21 or later
\startplaceformula[reference=formula:mass,list={Mass-energy equivalence}] \startformula e=mc^2 \stopformula \stopplaceformula