Output type and wiring decision
The E3S-AT71-L: The output is light-on/dark-on selectable — that's a two-wire DC or three-wire DC configuration depending on the exact model variant. The selector switch or wiring option lets you invert the output logic without adding a relay or PLC NOT instruction. For a field-service swap, that means you don't have to re-program the controller if the old sensor was wired dark-on and the replacement defaults to light-on.
Sensing range — what it actually means
The sensing range for the E3S-AT71-L depends on the sensing mode. The exact figure is listed in the Omron datasheet for this specific model suffix.