Is "Status Information Letter" necessary for N-400 application? bolomi2012-08-16 17:41:20

When I read   USCIS Document Checklist for Form N-400, Application for Naturalization (link, http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=6f547db185e43110VgnVCM1000004718190aRCRD&vgnextchannel=11616c854523d010VgnVCM10000048f3d6a1RCRD)

It is said that,

If you did not register with the Selective Service and you (1) are male, (2) are 26 years old or older, and (3) lived in the United States in a status other than as a lawful nonimmigrant between the ages of 18 and 26, send:

• A "Status Information Letter" from the Selective Service (Call 1-847-688-6888) for more information.