A link might be useful
Found a resource on the USCIS web. Don't know if it is out of date. Hopefully it helps a bit.
http://www.uscis.gov/files/nativedocuments/NSC_Filing_Tip_3_08_04.pdf
Found a resource on the USCIS web. Don't know if it is out of date. Hopefully it helps a bit.
http://www.uscis.gov/files/nativedocuments/NSC_Filing_Tip_3_08_04.pdf