PER_CHK_ACTION_OCC_ITEMS: which table and column does foreign key column OBJECT_CHANGE_ID reference?

Summary:

I'm looking for information about column OBJECT_CHANGE_ID in table PER_CHK_ACTION_OCC_ITEMS. Which table and column does this column refer to?

Content (required):

I was under the impression that PER_CHK_ACTION_OCC_ITEMS.OBJECT_CHANGE_ID referenced HRC_EVT_OBJ_CHANGES.CHANGE_ID.

However, I've found a few values in OBJECT_CHANGE_ID that don't exist in HRC_EVT_OBJ_CHANGES.CHANGE_ID, thus violating referential integrity.

Can anyone confirm or deny my assumption, provide the correct reference, or confirm that records from HRC_EVT_OBJ_CHANGES can just be deleted, without cascading or setting null in dependent tables?