retention policy and borws policy

Its all ducumented in the Admin guide, however here is an extract for you.

Browinsing Policy;
You can recover a file that has an entry in the client file index by using the NetWorker client computer. Users can browse and mark files, and initiate data recovery. The NetWorker server does not remove the entry for a file until all the save sets that are dependent on the file have also exceeded their browse policies. In general, the entries for a full backup that are older than the browse policy are not removed until one backup cycle has passed. This extra time ensures that you can reconstruct a file to any point in time included in the browse policy period.

Retention Policy;
The NetWorker media retention policy specifies a period during which backed-up data is protected from an accidental overwrite. After the retention period is exceeded, the save set is eligible to change its status from recoverable to recyclable. The term recyclable means ¿eligible for recycling.¿ The save set¿s status, however, does not change to recyclable until it, and all the save sets that depend on it, have passed their retention policy. The NetWorker server keeps track of save set dependencies regardless of whether the dependent save sets are stored on the same or different volumes. The expiration of a save set¿s retention policy does not remove the save set¿s entries from the media database.