When you go to System Preferences -> Authorized values, there's a misleading description of NOT_LOAN values. NOT_LOAN is described to be "Reasons why a title is not for loan" When actually NOT_LOAN values are for items. So the description should be "Reasons why an item is not for loan". I guess it is theoretically somehow possible to use the not-loans values for titles (i.e. add them to bibliographical records), but as I see, it doesn't make much sense. This is about whether an item is available or not. Bibliographic records should not have data like this. The wrong description can be found both in /cgi-bin/koha/admin/authorised_values.pl and in /cgi-bin/koha/admin/authorised_values.pl?searchfield=NOT_LOAN I'm not sure if they come from the same source to both pages, or from different sources.