ECOTEST MKS-05 TERRA Operating Manual page 76

If the THRESHOLD button is being held down for more than three
seconds, the LCD displays the "Arch" symbols (Figure 16). Thus, it
becomes possible to proceed to the submode of measurement result saving
in the nonvolatile memory.
Figure 16 – LCD of the dosimeter (start of the submode of measurement
result saving in the nonvolatile memory)
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