@User: I am uncertain as to the physics/chemistry behind why the nitride poly cut is needed, but it is used to etch out the area under a poly contact (poly contacts to local interconnect above) to aid in forming a good electrical contact to the poly. "auto generated" in the table is referring only to the Magic layout editor; if you draw a poly contact in Magic, then the nitride poly cut will automatically be generated in the GDS output from that layout.