A value of 0 (zero) indicates success.
A negative value of -10000 or below indicates a very critical error, and further processing is usually impossible. Immediately shut down the whole process as it might be in an instable state.
Negative values between -1 and -9999 indicate critical errors, and further processing might be impossible.
A positive value of 1000 and above indicates non-critical errors, and further processing is possible. Return code values between 1 and 999 indicate warnings including possible issues with configuration settings, address input, or output.