[whatwg] [HTML5] Editorial: 3.10.18. The |sup| and |sub| elements

[Christoph Päper]

The second to last example should probably better read:

  <var>E</var> = <var>m</var> · <var>c<var><sup>2</sup>

or maybe, as the speed of light is a constant,

  <var>E</var> = <var>m</var> · c<sup>2</sup>.