https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=27365 --- Comment #2 from Didier Gautheron <didier.gautheron@biblibre.com> --- I my understanding it is From https://www.iso.org/obp/ui/#iso:std:iso:25577:ed-1:v1:en In 2001, the U.S. Library of Congress developed a framework for working with MARC data in an XML environment. The core of the framework is a MARCXML schema that allows lossless round-trip conversion of an ISO 2709 MARC 21 record and an XML-encoded MARC 21 record. IMO operative words are 'lossless round-trip' But I haven't access to the full norm, it's not free and anyway it' not available in France, you can't buy it! Moreover Koha may use xml --> iso and back in a couple of place. Yes by default ES is storing the whole record in iso2709 within its index. cf syspref ElasticsearchMARCFormat and Koha/SearchEngine/Elasticsearch.pm there's a f -- You are receiving this mail because: You are watching all bug changes. You are the assignee for the bug.