The green/gold distinction is about venues or delivery vehicles, not user rights or degrees of openness.
Open Access delivered by repositories is generally referred to as green OA.
Green OA can include:
- Self-archiving by authors. Independently from publication by a publisher, the author also posts the work to a website controlled by the author, the research institution that funded or hosted the work, or to an independent central open repository, where people can download the work without paying.
- Postprints. If the author posts the near-final version of their work after peer review by a journal, the archived version is called a "postprint". This can be the accepted manuscript as returned by the journal to the author after successful peer review.
Green OA is gratis for the author (see "Gratis and Libre Open Access" link below for definitions). Some publishers (less than 5% and decreasing as of 2014) may charge a fee for an additional service such as a free license on the publisher-authored copyrightable portions of the printed version of an article.
- OA repositories can be organized by discipline (e.g. arXiv for physics) or institution (e.g. DASH for Harvard). When universities host OA repositories, they usually take steps to ensure long-term preservation in addition to OA.
- OA repositories do not perform peer review themselves. However, they generally host articles peer-reviewed elsewhere.
- OA repositories can contain preprints, postprints, or both.
- A preprint is any version prior to peer review and publication, usually the version submitted to a journal.
- A postprint is any version approved by peer review. Sometimes it's important to distinguish two kinds of postprint: (a) those that have been peer-reviewed but not copy-edited and (b) those that have been both peer-reviewed and copy-edited. Some journals give authors permission to deposit the first but the not the second kind in an OA repository.
- OA repositories can include preprints and postprints of journal articles, theses and dissertations, course materials, departmental databases, data files, audio and video files, institutional records, or digitized special collections from the library...
- OA repositories provide OA by default to all their contents. Most now also allow "dark deposits" which can be made OA at any later date. This is useful in working with publishers who permit green OA only after an embargo period. Authors may deposit new articles immediately upon publication and switch them to OA when the embargo period expires.
- Authors need no permission for preprint archiving. When they have finished writing the preprint, they still hold copyright. If a journal refuses to consider articles that have circulated as preprints, that is an optional journal-submission policy, not a requirement of copyright law.
- If authors transfer copyright to a publisher, then OA archiving requires the publisher's permission. Most surveyed publishers (60+%) already give blanket permission for postprint archiving. Many others will do so on request, and nearly all will accommodate a mandatory green OA policy from the author's funder or employer. However, when authors retain the right to authorize green OA, then they may authorize green OA on their own without negotiating with publishers.
- When authors transfer copyright to publishers, they transfer the OA decision to publishers at the same time. Even if most publishers allow green OA, many do not. In addition, many qualify their permission and some add new restrictions over time, such as fees or embargo periods. For these reasons there is a growing trend among scholarly authors to retain the right to provide green OA and only transfer the remaining bundle of rights to publishers...
- Because most publishers already permit green OA, and because green OA is a bona fide form of OA, authors who fail to take advantage of the opportunity are actually a greater obstacle to OA than publishers who fail to offer the opportunity. Funders and universities are in a position to close the gap and ensure green OA for 100% of published work by their grantees and faculty...
- For a searchable database of publisher policies about copyright and archiving, see Project SHERPA.
- Because most publishers and journals already give blanket permission for green OA, the burden is on authors to take advantage of the opportunity. This means that authors may publish in nearly any journal that will accept their work (OA or non-OA) and still provide OA to the peer-reviewed text through an OA repository. (Unfortunately, the compatibility of green OA with publishing in most non-OA journals is still one of the best-kept secrets of scholarly publishing.)
- The most useful OA repositories comply with the Open Archives Initiative (OAI) protocol for metadata harvesting, which makes them interoperable...
- The two leading lists of OA repositories around the world are the Directory of Open Access Repositories (OpenDOAR) and the Registry of Open Access Repositories (ROAR).
