Unsigned64 is a 64-bit bitmask on the gmeta:Class registry entry marking which properties of that managed-object class are currently configurable (writable) by an administrator or API client. Because the bit layout differs per class, this field is mainly useful to management tooling deciding which columns of a given class it is allowed to PUT/set, rather than something an admin reads directly on a dashboard. For example, on the computeBlade class's gmeta:Class entry the bits corresponding to properties like adminPower or usrLbl would be set, while read-only inventory fields like serial would be clear.