Following the Cambridge Analytica scandal, Facebook has been clear about its intentions and attempts to restrict developer access to its platform to avoid a similar incident. Now, it has come to light that the social network introduced secretive new rules to ensure this was the case.

The ‘supplemental terms’ go beyond what developers had previously agreed in regards to building apps, according to Business Insider, citing a source. The terms exist in addition to the public policies displayed on Facebook’s developer site, but only developers can see them and have to sign a non-disclosure agreement.

Facebook’s ‘App Review’ page on its developer site refers to the supplemental terms but does not specify what they are. It says: “If we need you to agree to supplemental terms, we will ask you to provide an email address for a Business Signatory. We will email the signatory a link to a site displaying our Supplemental Terms for Extended Platform Products. The signatory can use the site to agree to the terms, after which we will email the signatory a copy of the agreement.”

The policies are said to give Facebook explicit permission to audit the information which developers are using, their processes, and controls. In addition, a developer’s own terms cannot contradict Facebook’s, and an app’s data security needs to be at its best.