Tim Rivera posted to the HTML Writers Guild on how to show footnotes above three (for up to three you can use the special characters ¹ and ² (which appear like this: footnote¹, footnote²)

For footnotes numbered above three, use either the HTML element SUP (which is not deprecated), or CSS, like this:

.sup {
vertical-align: super;
font-size: 0.6em;
}

⁴
<span class="sup">4</span>

...which look like this:
Footnote⁴ or footnote4

[Thanks to Tim Rivera]
-- posted by Palema on 3/03/2003