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What are metadata?
In order to assign DOIs, mEDRA needs to get some information about the documents and other content to which publishers will assign a DOI.
In other words, mEDRA will need metadata, that is "data about the data".
An example of metadata can be the name of the author of a book, the title of the book, the date of publication, the number of the issue of a journal within a certain magazine, the list of articles contained in the issue, etc.
For this reason, mEDRA created the ONIX-for-DOI-Registration Schemes, that are sets of metadata, managed in XML, gathering all the necessary information for a DOI registration. Not all the metadata contained in the spec are mandatory in order to assign a DOI, but only a set of elements called the metadata Kernel. The rest of metadata is optional.


What are mEDRA Metadata Subsets?
mEDRA made a selection among the whole ONIX metadata specification, creating eight different metadata subsets, in order to assign DOIs to:
  • monographic works
  • monographic products
  • monograph chapters works
  • monograph chapters products
  • serial articles as works
  • serial articles as manifestations
  • serial issues as works
  • serial issues as manifestations
To assign a DOI to a digital object as work means that separate DOIs are not assigned to each format of a given item. The print, PDF, and HTML versions of the same article will all share the same DOI. In this case, different versions of the same article can be pointed to from the response page to which the DOI resolves.
On the contrary, to assign a DOI to a digital object as product (or as manifestation) means that each format will receive a separate DOI.
More specific information about works and manifestations can be found in chapter nine of the DOI Handbook http://www.doi.org/hb.html.


What is ONIX?
The ONIX (Online Information Exchange) metadata specification (www.editeur.org) is the international standard for representing book, serial and video product information in electronic form. One of the key aims of ONIX is to provide a format for delivering structured data, through a much more highly structured model for information than other descriptive metadata formats, such as Dublin Core.
mEDRA metadata schemes were adopted as the official ONIX-for-DOI-Registration Schemes.