MathML generated by MathToWeb
A MathML example displaying the AMS-Latex extensible, non-pairing symbol \vert.

$\genfrac{}{}{0.1ex}{}{u^3}{4}{|}_1^2$ $\frac{u^3}{4} \vert_1^2$

<math xmlns="http://www.w3.org/1998/Math/MathML">
<mrow>
	<mfrac linethickness="1">
		<mrow>
			<msup>
				<mi>u</mi>
				<mn>3</mn>
			</msup>
		</mrow>
		<mn>4</mn>
	</mfrac>
	<msubsup>
		<mo>&verbar;</mo>
		<mn>1</mn>
		<mn>2</mn>
	</msubsup>
</mrow>
</math>