Another advantage of the MOP of Guaranį is its concern with security. The hierarchy of composition can be used to limit the ability of a meta-object to affect a base-level object. For example, a composer may decide not to present an operation to a meta-object, or to ignore results or replacement operations it produces. The composer can withhold a message to a component, reject a meta-object produced by a component at a reconfiguration or propagation request, or provide restrictive operation factories to its components, thus limiting their ability to create operations. Furthermore, since the identity of the primary meta-object of an object is not exposed, the hierarchy cannot be subverted.