Carrying out maintaining a software configuration management system are disclosed. In particular, a way to reverse prior revisions without removing their history in the server are described. When a client submits an undo command to reverse the effects of one or more revisions within a stated revision range of a file, the revision history is updated by submitting a new revision that effectively removes the changes embodied within the range of undone revisions. Implementing undoing prior revisions preserves the revision history for a file, in case there is a need to access the undone revisions at a later time.