Tombstones are records of deleted entities, and are included when services return not only lists of new and changed entities but deleted entities since the time specified in the delta token.

To support tombstones, the back-end response XML must include the <DELETED_ENTITIES> tag, which contains a list of deleted entities. The structure is the same as <ENTITY_SET>, which contains new and changed entities. Because tombstones record deletions, typically only the entity IDs are included in the results.