We would like to have our files Integrated in the national Danish Library system: https://bibliotek.dk/
They do harvest the data from our server via the OAI plugin. They do harvest the data in MARC21 and do then convert the data into a national format: danMARC2 (see here: https://da.wikipedia.org/wiki/DanMARC2 and here http://www.kat-format.dk/. Both pages in Danish, sorry).
The conversion normally works but they do have a problem. Their conversion fails. It seems that the plugin uses this as a leader: nmb a2200000Iu 4500
They do tell us that we should change the “m” in the leader to an “a”. They think that m is used for monographs and a is used for articles… We have found the place on our server where we can change the m to an a. But we would like to know if the change is correct.