Strange Markings on Export R51

[sebvox]

Does anyone know what these markings are on this R51?

[R51Fan2017]

The "CIP N" is a proof mark from the Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives. In other words, International Commission of Firearms Testing basically. The "N" I believe designates a "Nitro" proof. The "US DE 17" is probably the identifier for the exporter.