Accu-Chek Performa Owner's Booklet page 51

8. Press to set the level in the meter.
9. "OK" and the control result alternate on
the display if the result is in range. The
range is printed on the test strip
container label. "Err" and the control
result alternate on the display if the
result is not in range. Remove the test
strip and discard it.
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