The fingerprint database for each vault store group records the number of references to each SIS part that are present in the group's vault stores.

As users delete archived items, the number of references to a SIS part decreases. On the deletion of an item, if the number of references to a SIS part falls to 0 then Enterprise Vault checks whether the group's vault stores contain any references to the SIS part. Provided that no references remain, Enterprise Vault deletes the SIS part. If any references remain, Enterprise Vault retains the SIS part and generates an error in the Enterprise Vault event log.