Omron ZX Series Operation Manual page 148

FUN (Function) Mode
The setting operation will be canceled and the previous set value will be
displayed if the LEFT Key is pressed at the leftmost digit or the RIGHT Key
is pressed at the rightmost digit when setting a numeric value (flashing).
128
Section 4-5
The setting is canceled
and reset to the previ-
ous set value.
The display will stop
flashing.