Math Accents, Over and Underscripts

<applet code="geom.webeq.app.mdraw" codebase="../classes" width=300 height=100>
<param name="eq" value="x'=\bar{x}+\tilde{x}^2+\hat{x}+\vec{x}+\dot{x}+\ddot{x}">
</applet>

<applet code="geom.webeq.app.mdraw" codebase="../classes" width=400 height=100>
<param name="eq" value="\widetilde{\mathrm{SL}(2, \mathbf{C})} =
\overset{\text{$n$ terms}}{\overbrace{K_1 + \cdots + K_n}}">
</applet>