mspace2

negative space

W3C sample	WIRIS
	$H H$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mstyle mathbackground="#ccffff">
    <mi>H</mi>
    <mspace width="-10px"/>
    <mi>H</mi>
  </mstyle>
</math>

Author: Design Science, Inc. (D. Doyle, E. Cannon, E. Tabacman, R.Miner)