baseline	aligns baselines of element and with the parent's baseline
middle	aligns vertical midpoint of element with parent's baseline plus half the x-height (height of letter "x") of the parent
sub	subscripts the element
super	superscripts the element
text-top	aligns tops of element and top of parent element's font
text-bottom	aligns bottoms of element and bottom of parent element's font
top	aligns top of element with tallest element on the line
bottom	aligns bottom of element with lowest element on the line

x²³⁴⁵⁶ Nesting is possible!

Result is different in all 5 main browsers

<p style="font-size:96pt">x<sup style="font-size:smaller">2
                           <sup style="font-size:smaller">3...