ISBN for books
An ISBN identifies a particular title, edition and format of a book. Booksellers, libraries and distributors often require one. You can learn more from the International ISBN Agency.
A book can have both an ISBN and an SPSN. Use an ISBN wherever a seller, library or local rule requires it.
DOI for digital and research work
A Digital Object Identifier provides a lasting link to a digital item. It is widely used in research and professional publishing.
An SPSN opens an SPSN public page rather than acting as a DOI link. A digital publication can use both.
ISSN for journals and other continuing publications
An ISSN identifies a continuing publication such as a journal, magazine or newspaper. An SPSN may identify a separate issue or standalone work, but it does not replace an ISSN for the continuing publication. Learn more from the ISSN International Centre.
ISMN for printed or digital music
An ISMN identifies publications of written music in print or digital form. If an ISMN is required, an SPSN can be used as an additional number, not a replacement. Learn more from the International ISMN Agency.