<SUB> | NN 2 IE 3 HTML 3.2
<SUB>...</SUB> | End Tag: Required
The SUB element is a typographical element that instructs the browser to render its content as a subscript in a font size consistent with the surrounding content. Browsers tend to render this content in a smaller size than surrounding content.
Example
    <P>"Heavy water" (H<SUB>3</SUB>O) has one more hydrogen atom
    than regular water.</P>
Object Model Reference
IE | [window.]document.all.elementID