Dear Chris, briefly: it works! many thanks for your kind advice! :-) Now, a more extensive summary for the possible benefit of other future passers-by (and for my own reference). My problem was I could not properly edit existing items (or edit newly added items) for biblio records belonging to either of two co-existing Koha frameworks. "Old" framework complies with Koha 2.x (and has been inherited by a problematic backup, not properly upgraded for various reasons, some of which disastrous), while "new" framework complies with Koha 3.14 (my present installation). Old framework is my current default here (as most of my records still belong to that framework). Chris pointed out that frameworks prior to 3.x collected item specifications in some subfields of the MARC 952 tag, already in the MARC record (both binary and xml), while more recent frameworks deal with (a lot of more) item information only within the "items" mysql table of the Koha database. However, individual columns of such table are mapped onto specific 952.x subfields. This is indeed described in detail here: http://wiki.koha-community.org/wiki/Holdings_data_fields_(9xx) Chris suggested that I should first remove/strip all items information from the MARC record of each biblio record, which can be done (with some care) through the migration script misc/maintenance/remove_items_from_biblioitems.pl --run (reminder: prepend sudo and the appropriate environment variables, such as PERL5LIB=/usr/share/koha/lib KOHA_CONF=/etc/koha/sites/<your Koha instance>/Koha-conf.xml ) (individual records can be modified by adding the a command parameter such as --where="biblioitemnumber=2388" ; this follows a MySQç syntax) Rebuild the zebra index with sudo koha-rebuild-zebra -v -f Then, I had to modify existing Koha-to-MARC mappings in the old framework for nearly all 952.x subfields, and add all the ones which existed in the new framework but were absent in the old framework, so that all subfields under the 952 tag looked identical in both the old and the new framework. (New framework supersedes the old.) The zebra index must be rebuilt again (I did it several times, as I kept adding/editing subfields, in order to see whether things were working properly). I can now edit/add existing/new items in the new+old/new framework, and see them in the Opac at the correct position (no date showing in the place of replacement cost or itemnumber instead of a URI ... ). Many thanks once more! Giuseppe.