Our little state (hint: starts with "V") has implemented an interlibrary loan system that seems to be unable to use Z39.50 correctly to query Koha in order to determine an item's availability. I'll try to describe the problem and then ask if there's a workaround in Koha. The state ILL system, called CLOVER, is able to use Z39.50 to query our library's Koha installation to determine whether an item is in our catalog. We told the state to use the MARC 952$r field returned by Koha (actually Zebra, if I understand correctly) to determine whether the item is available. This field contains the item's due date. If it is present and contains a date, the item is NOT available. If it is not present, the item IS available. But apparently, CLOVER is not able to handle a MARC field that is present sometimes and not at other times. It requires that the field be present ALL the time. That is the explanation given to us by the state when we asked why CLOVER wasn't working correctly (it keeps issuing requests for books that it had already requested). This seems like a serious bug, because there are at least 80 other Koha installations in our state. Unfortunately, CLOVER is closed-source and proprietary, so there seems to be no way for the state to fix the problem. Is there some workaround that I can implement in Koha and/or Zebra to force the 952$r field to be present in all records returned in response a Z39.50 query? I think CLOVER might work if 952$r were present but blank for items that are available. Thanks in advance!