Comment 8 for bug 1754455

I'm testing this with some export that I will need to do in May, and it occurred to me that an additional feature that would be nice to have, that this branch does not provide, would be to delete tags from the output based on subfield values. My main use case would be to delete 856 tags where the subfield 9 is not for one of the libraries whose records I am exporting.

I will add that feature and write ups some release notes, which this branch needs.