See: ANNEXES to the Proposal for a REGULATION OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on a Union Code on the rules governing the movement of persons across borders (Schengen Borders Code) (codification) (COM
See: ANNEXES to the Proposal for a REGULATION OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on a Union Code on the rules governing the movement of persons across borders (Schengen Borders Code) (codification) (COM 8-2015, ANNEXES, pdf). Including: “Standard form for refusal of entry at the border” which says on page 13: “X is considered to be a threat to public policy, internal security, public health or the international relations of one of more of the Member States of the EU.”
See also the Commission Decision: COMMISSION IMPLEMENTING DECISION of XXX replacing the Annex to Commission Implementing Decision 2013/115/EU on the SIRENE Manual and other implementing measures for the second generation Schengen Information System (SIS II) (pdf)
And see: New measure implementing SIS II: Very detailed, from Commission SIRENE Manual: ANNEX to the COMMISSION IMPLEMENTING DECISION replacing the Annex to Commission Implementing Decision 2013/115/EU on the SIRENE Manual and other implementing measures for the second generation Schengen Information System (SIS II) (53 pages, pdf)