The C1TabsExtender control is generally used to break content into multiple sections that can be swapped to save screen real estate.
C1TabsExtender Markup
The following markup creates C1TabsExtender control. Set the TargetControlID property to attach the extender to a control.
<cc1:C1TabsExtender ID="Panel1_C1TabsExtender" runat="server"
TargetControlID="Panel1">
</cc1:C1TabsExtender>