From the page Actions
menu, select Spec Structure History.

The Specification Structure History page lists the connect and disconnect
history for the objects in the Specification Structure:
Name. The name of the object on the From side.
Action. The action performed between the From
and To objects. Values can be connect or disconnect.
To Object. The object on the To end of the
relationship.
User. The user that performed the connect or
disconnect action.
Date. The date on which the Specification Structure
was modified.