What does the term 'Tombstone' specifically refer to in the context provided?

In the context provided, the term "Tombstone" specifically refers to a file replacement mechanism used within certain database management systems and directory services. Tombstones serve to mark items that have been deleted or are no longer in use, allowing the system to manage data integrity and replication effectively.

When an entry is deleted in a system that uses tombstones, it is not immediately removed; instead, a tombstone marker is created to indicate that the item has been deleted. This approach can help prevent issues that may arise from immediate deletion, such as inconsistencies during data replication across systems. When the time for retention specified by the system expires, the tombstone is fully purged from the database. Thus, the use of tombstones is vital in ensuring that systems maintain data consistency and integrity even in the event of entry deletions.