ISO/IEC TS 22424-2:2020 pdf download – Digital publishing — EPUB3 preservation — Part 2: Metadata requirements.
6.5? Work? and? publication? identifiers According to the EPUB specification, each EPUB publication shall have a (globally) unique identifier. However, revised publications do not need to have a new standard identifier if only minor changes have been made, such as metadata updates or errata fixes. In such cases, usage of release identifiers (which consist of e.g. ISBN and the publication date) is recommended in the EPUB specification, but not mandatory. This approach is similar to the one in the ISBN standard. In order to facilitate long-term preservation, each rendition and version of an EPUB publication submitted to an OAIS archive shall have an identifier, and the submission agreement or other guidelines shall specify the identifier systems allowed. If the archive’s repository system cannot process EPUB release identifiers (for instance because the system assumes each e-book has its own ISBN or other standard identifier), release identifiers assigned by the publisher should be replaced with identifiers the OAIS archive is able to use during pre-ingest by the producer. Identifiers belonging to the different manifestations of a work should be included in the metadata records describing these manifestations. In addition, a work identifier may be used in order to facilitate interlinking of manifestations of a work. NOTE 1 ISBN is universally used for identification of books, but there is no widely used identifier system for textual works.
The submission agreement shall specify the encoding of publication identifiers. There are at least two encoding options, of which one shall be selected in the agreement: 1) An identifier is included in the Dublin Core metadata embedded in the EPUB publication, as specified in the EPUB publications specification. The EPUB specification requires that the identifier of a publication is provided in the Dublin Core element identifier. The EPUB META element may be used to indicate the identifier type, using an authorized list such as ONIX Code List 5 11) . 2) Identifier is expressed using the <premis: objectIdentifier> element. If so, PREMIS encoding shall specify the identifier type. NOTE 2 It is possible that digital preservation systems are unable to handle EPUB release identifiers. For instance, their duplicate-check algorithms could expect standard identifiers such as ISBNs for books. It is possible to build a digital preservation system capable of using EPUB release identifiers, but as of this writing no such systems exist in the library sector.