這個是普通的補材料嗎？還是像重新準備140 一樣啊？

just got email from USCIS,

On June 8, 2009, we mailed a notice requesting additional evidence or
information in this case I140 IMMIGRANT PETITION FOR ALIEN WORKER. Please
follow the instructions on the notice to submit the requested information.
This case will be in suspense until we receive the evidence or the
opportunity to submit it expires. Once we receive the requested evidence or
information and make a decision on the case, you will be notified by mail.
If you move while this case is pending, call 1-800-375-5283 to update your
address

my situation is : NIW, is it RFE ? how to deal with this RFE? need what
materials to reprove ?

這個是普通的補材料嗎？還是像重新準備140 一樣啊？
要推薦信和文章啊？
thanks !