Complex sentence: The standard does not evaluate the behavior of the flashlight output during run time; a regulated flashlight may run at only a slowly declining output and then abruptly cut off, but unregulated types may have steeply-declining light output after only a short time.
Split into simpler sentences: The standard does not evaluate the behavior of the flashlight output during run time. A regulated flashlight may run at only a slowly declining output and then abruptly cut off, but unregulated types may have steeply-declining light output after only a short time.