The gold road
The gold road to open access – also known as gold OA - refers to the primary publication of scientific and scholarly works as articles in OA journals, as OA monographs, or as contributions to openly accessible edited volumes or conference proceedings. These texts normally undergo the same quality assurance process as their closed-access counterparts - usually peer review or editorial review. As a rule, the author concludes a publishing agreement with the publisher that lays down the rights of use granted to the journal or the publisher and the conditions of use that will apply to the openly accessible content. This agreement is often supplemented by an OA publishing agreement by means of which the author can grant users broader and precisely specified rights.
Both OA and closed-access publications must be funded. The options for funding OA publications are comparable to those used to fund closed-access publications. They include advertising and sponsoring, unpaid support from the scientific community and scientific or scholarly institutions, voluntary work, and the sale of print copies. Cross-financing is also an option that is sometimes availed of, especially by commercial publishers who wish to try out the gold OA business model and who cross-finance new OA journals with revenue from their subscription journals. Publication fees, also known as article fees or article processing charges (APCs), are cited as a typical gold OA funding model, although such charges are also common in the closed-access publishing context. APCs are payable per accepted and published article. In the OA context, they are often combined with institutional memberships: if the submitting author is affiliated to a member institution of an OA publisher, their APCs are borne in full or in part by that institution.
The green road
The green road to open access - also known as self-archiving or green OA - refers to the practice of providing OA to a version of a work published in a closed-access journal or with a closed-access publisher by depositing it in an openly accessible institutional or disciplinary repository. A broader definition of green OA also includes the practice of making works available on the author's personal website. Self-archiving may take place at the same time as, or after, publication of the work. Documents that can be self-archived include preprints and postprints of scholarly articles as well as other document types such as monographs, research reports, and conference proceedings.
A preprint is the (as yet) unrefereed version of a scholarly or scientific work. In other words, the quality of the work has not yet been conclusively assessed by peers, and the manuscript has not yet been recommended for publication. Hence, "preprint" generally refers to the version of the manuscript that was submitted for publication to a journal or a publisher.
In contrast to the preprint, the postprint is the version of a manuscript that has successfully undergone peer review and has been accepted for publication. There are two types of postprint. On the one hand, a postprint may be the publisher's version, or the official version of record, which is completely identical to the formally published version. On the other hand, a postprint may be identical to the publisher's version in terms of content but may differ from it in terms of format, layout, or pagination. In the latter case, it is referred to as the accepted author manuscript (AAM). The AAM may also be the uncorrected proof, which has yet to receive final author and publisher approval.
Because journals and publishers vary in their willingness to allow their authors to self-archive the postprint or the preprint of the published work, legal problems may arise. The SHERPA/RoMEO database provides an overview of publishers' self-archiving policies.
In discussions on OA, three types of self-archiving are distinguished. On the one hand, access can be provided to works by depositing them in an institutional repository. In this case, authors have the opportunity to deposit their scientific and scholarly texts in a multi-disciplinary repository maintained by their institution (e.g. university). In disciplinary repositories, on the other hand, scientific and scholarly documents from one discipline or field, for example, are thematically bundled and made available, irrespective of the institution to which the author is affiliated. A third variant of self-archiving is to post the work to one's personal website. However, this approach means that the documents in question are not as visible as they would be if they were archived in an institutional or a disciplinary repository. What is more, their long-term availability is not assured. For this reason, posting works to one's personal website is frequently not recognized as a form of green OA. This is the case, for example, in the Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities.
There are also “link roads” between gold and green OA. For example, the repository Social Science Research Network (SSRN) enables authors to provide open access to a version of their published journal articles and to self-archive preprints of their papers in SSRN before submitting them to a SSRN partner journal. The epijournals in mathematics are another example. These OA journals use the infrastructure of repositories in the following way: Authors make their manuscripts available via the OA repository arXiv or Hyper Articles en Ligne (HAL) before submitting them to an epijournal. If the submission is accepted for publication after peer review, the published journal article is stored along with the preprint in the repository. Closed-access publishers use arXiv in a similar way by enabling self-archived manuscripts to be automatically fed into their own submission workflow. The self-archiving of preprints prior to publication in a journal also has characteristics of gold and green OA. In the same way, the primary publication of documents such as dissertations or working paper series in a repository is also a hybrid form of the aforementioned strategies. Because they are primary publications, they can be regarded as gold OA. However, OA is provided via repositories, which usually serve as a vehicle for green OA.