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- the snapshotId is actually the relevant jobExecutionId
- the instances.id is near the bottom in the field named externalIdsHolder externalIdsHolder - unfortunately it would appear that this field is not searchable and so it will be necessary to collect the records.id immediately after POSTing and stow it along with the corresponding instances.id in a MySQL db table in order to be able to overlay those records later
- both the records.id and instances.id are included in a 999 that wasn't in the original MARC and isn't in the records.rawRecord.content field
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