The Czech National Agency for ISBN and ISMN would like to inform you about the new principles of assigning ISMN that came into force this year.
For music books that are in terms of their content in between a music book and a classical book category (e.g. songbooks, music books with extensive textual or image material), it is no longer possible to assign both an ISMN and an ISBN. Assign either an ISMN or an ISBN at your discretion. In case of doubt, it is preferred to assign an ISMN.