AEMC 721 User Manual page 38

Recording is possible for up to 24 hours when using a fresh battery, and
limited to 8 hours in %THD and %DF.
During record mode, a beep indicates the capture of each new minimum
and maximum value. When recording current or voltage measurement
information, specific segments on the analog bargraph will blink indicating
the current status of the MIN and MAX values.
In MIN/MAX Recording, the bargraph indicates Arms or Vrms. The MIN
and MAX values are also indicated and blink.
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Harmonic Meter Model 721