Backup retention question

[Dollens, Bruce]

We are wanting to setup a new policy domain and management class for our
Active Directory backups.  We want to keep only 7 days of backups. If I
wanted to accomplish this would the management class look like this? (I
have a difficult time with this part of it for some reason).

                  Versions Data Exists: 7
              Versions Data Deleted: 7
              Retain Extra Versions: 7
              Retain Only Version: 7

Thanks!