Hach DR/820 Instrument Manual page 43

SECTION 5,
continued
A flashing question mark icon will appear in the lower-right
portion of the screen as an additional step to avoid erasing all data
if the choice was made erroneously.
5. Confirm this action by pressing the key or, if this is
ENTER
not the desired action, press the key.
EXIT
After the key is pressed, the instrument automatically
ENTER
erases all stored data and returns to the last used program.
41