Files within the specified number of layers will be flagged for scanning.
If you set the limit to two layers:
Worry-Free Business Security Services will ignore 333.txt because it is located on the third layer.
Worry-Free Business Security Services will flag the following files for scanning and then check Rule 3:
DDD.txt (located on the first layer)
CCC.xls (located on the second layer)
111.pdf (located on the second layer)