The Public Library of Science (PLOS), The Scholarly Publishing and Academic Resources Coalition (SPARC), and the Open Access Scholarly Publishers Association (OASPA) developed the “How open is it?” guide, which shows the spectrum between open access and closed access"HowOpenIsIt?®" Open Access Spectrum (OAS) guide; see https://www.plos.org/how-open-is-it. The figure below shows where Cochrane Reviews fit onto this open-access spectrum for gold* and green open access (updated March 2016). The categorization is the same for Cochrane protocols, except that from February 2016, protocols are free to view upon publication as part of the green open access policy.
*Note: The gold open access categorizations would change if published with a CC BY licence.
Figure 1. How open is it? Gold and green access in the CDSR