[Koha] Koha and OAI

Hello, translating/writing Koha 3.0 french documentation, I configured Koha as OAI repository with system preferences OAI-PMH. It seems to work quite fine, however I wonder how the sets defined in sys pref OAI-PMH:Set are used : - I didn't see the correspondence between Set and any field of biblio, or document types. - I didn't find in oai.pl a query where Sets are involved, - and the xml response to oai verb oai.pl?verb=ListIdentifiers&metadataPrefix=oai_dc&set=name_of_set is the same for every set value. Does anyone know about that ? Thanks, Laurence Lefaucheur ---------------------- Laurence Lefaucheur Biblibre http://www.biblibre.com