== mathstackers ==
ConTeXt has a nice structure called {{code|1=mathstackers}} in order to define new math commands in which some characters are stacked over another one. For more information refer to {{src|math-stc.mkiv}}.
Here are the built-in commands \type{\mathover} and \type{\mathunder}:
$\mathover[symbol]{"2217}{A}$, % 2217 is a circlean asterisk$\mathover[symbol]{"2218}{A}$, % 2218 is an asteriska circle
$\mathover[symbol]{"2219}{A}$, % 2219 is a bullet
$\mathunder[symbol]{"2217}{A}$,
</texcode>
When typeset in {{code|1=mkiv}} one can see that the command {{code|1=\interior{K}}} shows the letter K with a small circle above it.
[[Category:Math]]