Some of you who have submitted content to us during the first two months of 2021 may have experienced content registration delays. We noticed; you did, too.
The time between us receiving XML from members, to the content being registered with us and the DOI resolving to the correct resolution URL, is usually a matter of minutes. Some submissions take longer - for example, book registrations with large reference lists, or very large files from larger publishers can take up to 24 to 48 hours to process.
TL;DR: We have a Community Forum (yay!), you can come and join it here: community.crossref.org.
Community is fundamental to us at Crossref, we wouldn’t be where we are or achieve the great things we do without the involvement of you, our diverse and engaged members and users. Crossref was founded as a collaboration of publishers with the shared goal of making links between research outputs easier, building a foundational infrastructure making research easier to find, cite, link, assess, and re-use.
Event Data uncovers links between Crossref-registered DOIs and diverse places where they are mentioned across the internet. Whereas a citation links one research article to another, events are a way to create links to locations such as news articles, data sets, Wikipedia entries, and social media mentions. We’ve collected events for several years and make them openly available via an API for anyone to access, as well as creating open logs of how we found each event.
2020 wasn’t all bad. In April of last year, we released our first public data file. Though Crossref metadata is always openly available––and our board recently cemented this by voting to adopt the Principles of Open Scholarly Infrastructure (POSI)––we’ve decided to release an updated file. This will provide a more efficient way to get such a large volume of records. The file (JSON records, 102.6GB) is now available, with thanks once again to Academic Torrents.
A DOI (digital object identifier) is a persistent identifier attached to content (such as an article, chapter). It’s displayed as a link, and looks like this:
As you can see, it has several parts:
https://doi.org/ = the DOI resolver: makes the DOI a URL (actionable)
10.5555 = prefix: assigned by Crossref
YFRU1371 = suffix: decided and assigned by the member, should be opaque.
The prefix and suffix make a DOI, and with the DOI resolver form a DOI link. The suffix should be opaque.
An opaque identifier does not encode or describe any information about the work, such as publication name, date, or ISSN. It’s important to avoid encoding any human-readable information, so if any of the metadata associated with the DOI changes, there is no confusion between the information encoded in the DOI and that found in its metadata.
For example, 10.5555/njevzkkwu4i7g is opaque, but 10.5555/ogs.2016.59.1.1 encodes information which may change and therefore could be confusing or misleading in future.
The DOI link uses the DOI resolver to look up the registered URL for the item. This shows why it’s important to keep the metadata up-to-date, so that the DOI points to the correct URL for the item.
DOIs at different levels
A DOI may refer to a journal or book (a title-level DOI), or to a specific article or chapter.
Journals and DOIs
Like a set of nesting dolls, a journal may be made up of volumes, each containing a number of issues, each containing a number of articles. You can assign a DOI at each level, for example:
journal-level-DOI (sometimes called the title-level-DOI) 10.5555/QYPF2031. Like an ISSN, it refers to the whole journal
The role of the journal-level-DOI, volume-level-DOI, and issue-level-DOI is to link persistently to a point in the journal structure. These DOIs do not have any associated content, and it does not cost anything to register these DOIs.
However, article-level-DOIs do have associated content, and therefore a fee applies to register these DOIs.
Books and DOIs
Like a set of nesting dolls, a book may be made up of chapters. Again, you can assign a DOI at each level, for example:
book-level-DOI (sometimes called the title-level-DOI) 10.5555/ZAAR1365. Just like an ISBN, it refers to the whole book.
Both book-level-DOIs and chapter-level-DOIs have associated content, and therefore a fee applies to register these DOIs.