When each line of code is written it is surrounded by a sea of context: who in the community this is for, what problem we’re trying to solve, what technical assumptions we’re making, what we already tried but didn’t work, how much coffee we’ve had today. All of these have an effect on the software we write.
By the time the next person looks at that code, some of that context will have evaporated.
It turns out that one of the things that is really difficult at Crossref is checking whether a set of Crossref credentials has permission to act on a specific DOI prefix. This is the result of many legacy systems storing various mappings in various different software components, from our Content System through to our CRM. To this end, I wrote a basic application, credcheck, that will allow you to test a Crossref credential against an API.
Subject classifications have been available via the REST API for many years but have not been complete or reliable from the start and will soon be deprecated.
The subject metadata element was born out of a Labs experiment intended to enrich the metadata returned via Crossref Metadata Search with All Subject Journal Classification codes from Scopus. This feature was developed when the REST API was still fairly new, and we now recognize that the initial implementation worked its way into the service prematurely.
Crossref and DOAJ share the aim to encourage the dissemination and use of scholarly research using online technologies and to work with and through regional and international networks, partners, and user communities for the achievement of their aims to build local institutional capacity and sustainability. Both organisations agreed to work together in 2021 in a variety of ways, but primarily to ‘encourage the dissemination and use of scholarly research using online technologies, and regional and international networks, partners and communities, helping to build local institutional capacity and sustainability around the world.
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
volume-level-DOI 10.5555/FFFU4804
issue-level-DOI 10.5555/QKLE5634
article-level-DOI 10.5555/CNBT7653
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.
chapter-level-DOI 10.5555/TFWD2627
Both book-level-DOIs and chapter-level-DOIs have associated content, and therefore a fee applies to register these DOIs.