The measurement range of an external sensor, such as a probe, RTD or Thermocouple, can often exceed the operating range of a data logger. A probe, RTD, or Thermocouple may for example have a range of -200 degrees Celsius to 260 degrees Celsius. This only means the probe itself can be subjected to those temperatures.
If the Operating Environment is specified at -40 degrees Celsius to +140 degrees Celsius, then the data logger will fail if operated it beyond that range. Additionally, exposing a battery beyond its operating limits can be extremely dangerous. In order to prevent catastrophic failure, danger to people or property, and damage to the data logger, the data logger in the range specified in the Operating Environment at all times.