The following example shows the arc object:
<arc name="Arc2" height="2" width="2" left="138" top="222" visible="true" wallpaper="false" isReferenceObject="false" backStyle="solid" backColor="aquamarine" foreColor="#00C000" lineStyle="solid" lineWidth="1" patternStyle="none" patternColor="#00C000" startAngle="3.14159265358979" endAngle="3.14159265358979">
<transform scaleWidth="-0.5" scaleHeight="-0.5" shearWidth="0" shearHeight="0" offsetWidth="138.5" offsetHeight="222.5" />
<animations>
<animateRotation expression="TST2" rotationMin="0" rotationMax="358" centerOfRotation="(90,40)">
<defaultExpressionRange />
</animateRotation>
</animations>
</arc>