The C1ContextMenu component is a menu (it derives from the C1CommandMenu base class) that can be attached to an arbitrary control as a context menu. To facilitate this, the C1CommandHolder (which always exists on a form using C1 menus) is an IExtenderProvider providing a C1ContextMenu property of the type C1ContextMenu to all controls on the form.
Note that a C1ContextMenu can be used in other menus in exactly the same way as its base class C1CommandMenu. Thus if you want to use the same menu as a submenu in the main menu system and as a context menu, just link C1CommandLink to the same C1ContextMenu in both places.
For more information about using the C1ContextMenu, please see Context Menu Tasks.