|Contained in||Inline elements, block-level elements|
The SUP element is used for superscripts. Since SUP is inherently presentational, it should not be relied upon to express a given meaning. However, it can be useful for mathematical exponents where the context implies the meaning of the exponent, as well as other cases where superscript presentation is helpful but not required. For example:
The rent is due on the 1<SUP>st</SUP> of each month.
An example of a quadratic polynomial is <STRONG>3<VAR>x</VAR><SUP CLASS=exponent>2</SUP> + 5<VAR>x</VAR> - 7</STRONG>.
The following two examples are ambiguous when presented on a browser incapable of superscript text:
2<SUP CLASS=exponent>4</SUP> = 16
sin<SUP CLASS=exponent>2</SUP><VAR>x</VAR> + cos<SUP CLASS=exponent>2</SUP><VAR>x</VAR> = 1
There is no simple solution for this problem. One could use notation such as 2^4 to represent "two raised to the exponent four." If it gains browser support, MathML should provide a more suitable solution in the future.