CKReferenceMBS.ActionDeleteSelf = 1

Type	Topic	Plugin	Version
const	CloudKit	MBS Mac64bit Plugin	16.5

One of the actions.

The delete action for referenced records.
Deleting a record also deletes any records containing CKReferenceMBS objects that point to that record. The deletion of the additional records may trigger a cascade deletion of more records. The deletions are asynchronous in the default zone and immediate in a custom zone.

CKReferenceMBS.ActionNone = 0

Type	Topic	Plugin	Version
const	CloudKit	MBS Mac64bit Plugin	16.5

One of the actions.

No action when a referenced record is deleted.
Deleting a parent record does not delete the children that refer to that parent. The CKReference object still contains the ID of the deleted record and is not updated automatically.