In addition to the alarm you can see:
if you are exercising above heart rate zone. 
if you are exercising below heart rate zone.
Swapping the Heart Rate Limits
Press and hold the up button. Repeat until the desired limits are displayed. In the Interval Training mode the limits are automatically swapped when the phase changes to the preset limits.
You have three optional Exercise modes depending on the selected exercise:
•BasicUse
•Interval Training Set (Int On)
•BasicSet (Int OFF)
The following functions can be used during all three optional Exercise modes.
Illuminating the Display
Press the signal/light button.
After you use backlight once in the Measure mode, the receiver automatically illuminates the display if you: start or stop the exercise session, store lap information and at the end of an interval and a recovery calculation.
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