[OAI-implementers] Moving records in and out of sets

[Alan Kent]

Sorry, I have been too busy (too lazy?) to read the spec carefully, but
someone ask me recently what happens if a harvester uses sets to harvest
a subset of a collection, and then a record moves in and out of that set.
I could not work it out from a quick skim read of what I think are the
relevant sections of the spec.

If a record starts in the set, it will be harvested.

If it then is updated so that it no longer belongs to that set, it
wont be returned in the next harvest - no delete (the record has not
been deleted), no update (it does not match the set), etc.

If the record is then updated (but not put back into the set), it will
not be returned (its not in the set being harvested).

Then if its updated and put back into the set, the harvest should pick
it up again as being updated and in the set.

If it is updated again and removed from the set, then deleted, the harvest
will not pick it up because it was not in that set when it was deleted.

Does the above make sense? Is there something I am missing? Or is it
that records can never change their set membership? (Or is it just
an unfortunate little aspect of OAI that is not a problem often enough
to make it worth worrying about?)

Thanks
Alan