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Environment data include all kinds of data which are not part of the event data. Usually environment data either stay the same for the whole job or change at a slower rate than event data. Example of the environment data could be configuration data read from XTC at the beginning of the job, EPICS data which is not updated on every event, and few other things. Environment data is represented for user code through the object of type pyana.event.Env. Its interface is described in the reference manual.

For some pieces of data one needs to specify data "address" which identifies (maybe partially) particular DAQ device which produced the data. This is needed because the instrument setup may include multiple devices producing the same data type. The DAQ defines a type which serves as a most specific device identification, the type is xtc.DetInfo in package pypdsdata. One can pass this DetInfo instance to a method which accepts device address to select that specific device. DetInfo object contains four essential pieces of information:

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