Here is information I found from IO's point of view. When I filled my application, I was not aware of it. Hope this will be usefull to others.
http://www.uscis.gov/propub/ProPubVAP.jsp?dockey=3119bf586c306404271999d9d3305b77
http://www.uscis.gov/propub/ProPubVAP.jsp?dockey=3119bf586c306404271999d9d3305b77