The cOAlition S has released an implementation guidance on Plan S. Eleven European research funding organizations published Plan S in September 2018. It defines ten principles for the transition by 2020 to open access.

The main roads for Plan S are:

• Publication in Open Access Journals or Platforms;
• Deposit of Versions of Record (VoR) or Author Accepted Manuscript (AAM) in Open Access repositories without embargo;
• Publication in ‘hybrid’ journals only under transformative agreements;

For the deposition of scholarly content in open access repositories: Preprint servers are not suffucient to be compliant.