Target represents any type of target, which can be tracked by ImageTrackerBaseBehaviour or other algorithms inside EasyAR.
The target id. A target id is a int number generated at runtime, it is valid (non-zero) only after a successful setup.
The target uid. A target uid is useful in cloud based algorithms. If no cloud is used, you can set this uid in the json config as an alternative method to distinguish from targets.
The target name. Name is used to distinguish targets in a json file.
The meta data. In a cloud returned target, the meta data is pre-set in the cloud server.
A set operation will set the data as string. It will erase previously set data or data from cloud.