O
Official rating certificate
公式歩度証明書／コウシキホドショウメイショ
官方评级证书
Official rating certificate
Bulletin officiel de marche
Glossary
Thematic
Technic
A document, issued by an Observatory or an official ratings bureau, that certifies the quality of a watch which has proven, in trials, to meet with a given standard. Only a watch that has received an official rating certificate can be called a chronometer.