data/mathematical/56.mml
<math xmlns='http://www.w3.org/1998/Math/MathML' display='inline'><semantics><mrow><msub><mstyle mathvariant="bold"><mi mathvariant="bold">F</mi></mstyle> <mi>r</mi></msub></mrow><annotation encoding='application/x-tex'>\boldsymbol{F}_r</annotation></semantics></math>