Hi Frederic, Thanks a lot for your prompt and precise reply.
USMARC ($record->as_usmarc) produces valid UNIMARC records.
Ah this is good news, thanks !
This way you can populate an ISO2709 MARC file that can be uploaded into Koha with bullkmarcimport.pl script.
2. After the initial import has been done, we will certainly want to refine it by using data from our national library, sch as leaders for instance (?), or perhaps or initial import won't be complete and we will want to add other things we did not at first to keep the first import possible. So, is the incremental modification of records possible and how ? Wil we have to export the records to marc, then modify them and re-inject them, or is it recommended to do things another way ?
It can work this way. You can also use Koha API to modify biblio records directly. Take a look at Biblio.pm Koha module. You will read all biblio records. For each biblio record, you will query your (our) national library. You will merge both records and write the result into your Koha DB.
Okay I see, thanks a lot for he pointer. In fact, could thissz biblio.pm module also be used for the initial immort, rather than using MARC directly ? According to you, how do these solutions compare ? And also, are there functionalities in Koha's web interface that could be used to enrich an existing bibliographic record (or set of existing bibliographic records) with data fetched, say, from a Z39.50 server ? Thanks again for helping, Sébastien.