These marks usually hide behind the central obverse tablet.
Fortunately (or unfortunately - depends on the perspective taken) screws often become lost.
Mark "0".
Another example of mark "0".
manchukuo awards and decorations
manchukuo order
manchukuo order oftheauspiciousclouds
marked order oftheauspiciouscloudsordeoftheauspiciouscloudsorder oftheauspiciousclouds with technical mark
卿雲勳章