Testing MathML msub: a_b a_i Testing MathML msup: d^b 2^{{\mathrm{a}}_x} {2^2}^x 2^{{\mathrm{y}}^{a_x}} Testing MathML mrow: d^{\left(\frac{a}{b}\right)} x^2+4*x+4/\frac{p}{q}=0 and then piling fractions with a user-defined line thickness... \genfrac{}{}{0.2ex}{}{\frac{\mathrm{alpha}}{a}}{\frac{\mathrm{beta}}{b}} , with this mfrac hanging here \frac{d*b^{\left(\frac{\mathrm{x\; +\; y}}{z}\right)}+p_y*q}{p^x*b_x+\frac{a+c}{d}} in the middle of a lot of running text to try to explain what this means to those who care to read.