# \stackrel

This can be used to stack something above something else; used in math mode.

  \stackrel{top}{bot}

The first argument, top, is typset immediately above the second argument, bot; the former is set in the same math style as a superscript.

For example

  H$_2$CO$_3$ $\stackrel{\rm heat} {\longrightarrow}$ H$_2$O + CO$_2$

will produce something like

heat
H CO   ------>  H O  +  CO
2  3            2        2

Note that the the \rm declaration is used so that "heat" is set in Roman face and not math italics.