Policy Memorandum: Eligibility for Members of the National Guard of the United States to Naturalize under Section 329 of the Immigration and Nationality Act and Acceptance of NGB Form 22 as Certification of Military Service for National Guard Veterans; Revision to the Adjudicator's Field Manual (AFM) Chapter 72.2(d)(3); AFM Update AD10-42 [open pdf - 2MB]
"This Policy Memorandum (PM) provides field guidance pertaining to members of the Army National Guard of the United States and the Air National Guard of the United States (hereafter 'National Guard') for purposes of naturalization under section 329 of the Immigration and Nationality Act (INA). This PM also provides field guidance and an AFM update on the acceptance of National Guard Bureau (NGB) Form 22, 'National Guard Report of Separation and Record of Service,' as certification of service in the Armed Forces for purposes of naturalization under section 328 or 329 of the INA."
Policy Memorandum: PM-602-0027
U.S. Citizenship and Immigration Services: http://www.uscis.gov/