[IUG] Link Maintenance Missing Some Bib Records?

["Stephen McLaughlin" <sMcLaughlin at sfpl dot org>]

I've run into a weirdness and I'm wondering if anybody else has seen
this, or knows what's causing it.

The first item of information is that we run link maintenance against
our entire database every day, it is run manually and the staff are
instructed to use the following menu choices:

B > BOTH rearrange attached records and update locations

and

A > ALL types of records -- item, order and checkin

So as far as I can tell, any change to the item, order or checkin
records attached to any bib record should cause changes in the bib-level
location field.

So far so good, right?

The next element in the story is that I've been trying to track down how
some bib records wound up with no item, order or checkin records
attached, since it doesn't seem to be happening by our regular database
maintenance procedures. This led me to discover some bib records that
have no attached records of any type, but still have a bib-level
location code. These are not busy or suppressed records. I ran link
maintenance against one such record, and no change was made to the
bib-level location field, even though there were no items, orders or
checkins attached. It's like link maintenance is just skipping the bib
for no reason.

Am I missing something terribly obvious? Is there some glitch in link
maintenance? I've looked in the manual, and I cannot see any reason why
the program would be skipping these bib records. What's worrisome is
that there seem to be more and more bib with these "phantom" holdings.

Help, Mister (or Ms.) Wizard!

Steve McLaughlin
The Missing Link?
San Francisco Public Library