Also, FWIW, here's an excerpt from the OAI-PMH (protocal for metadata
harvesting):
http://www.openarchives.org/OAI/openarchivesprotocol.html#DeletedRecords
(This is a different protocol than the one I mentioned earlier -- OAI-ORE
-- and is widely implemented). Perhaps there is some useful wisdom here:
2.5.1 Deleted records
If a record is no longer available then it is said to be deleted.
Repositories must declare one of three levels of support for deleted
records in the deletedRecord element of the Identify response:
* no - the repository does not maintain information about deletions. A
repository that indicates this level of support must not reveal a deleted
status in any response.
* persistent - the repository maintains information about deletions
with no time limit. A repository that indicates this level of support must
persistently keep track of the full history of deletions and consistently
reveal the status of a deleted record over time.
* transient - the repository does not guarantee that a list of
deletions is maintained persistently or consistently. A repository that
indicates this level of support may reveal a deleted status for records.
If a repository does not keep track of deletions then such records will
simply vanish from responses and there will be no way for a harvester to
discover deletions through continued incremental harvesting. If a
repository does keep track of deletions then the datestamp of the deleted
record must be the date and time that it was deleted. Responses to
GetRecord request for a deleted record must then include a header with the
attribute status="deleted", and must not include metadata or about parts.
Similarly, responses to selective harvesting requests with set membership
and date range criteria that include deleted records must include the
headers of these records. Incremental harvesting will thus discover
deletions from repositories that keep track of them.
Deleted status is a property of individual records. Like a normal record,
a deleted record is identified by a unique identifier, a metadataPrefix
and a datestamp. Other records, with different metadataPrefix but the same
unique identifier, may remain available for the item.
--peter keane
