请教General Tips on Assembling Applications for Mailing的1条

Use the appropriate mailing address and mark both the envelope and the cover letter as to the form type. Example: I-129; I-130; I-690; I-698, etc.

请问这句话后半句不明白，我找到的cover letter的例子如下，但是找不到上面后半句话对应的部分，是不是       Type of Petition: I-140就是？另外，我没有Fax，是不是可以不写了？

ORIGINAL SUBMISSION                                                                                                 XX, Ph.D.
XXXXXXXXX
XXXXXXXXX
                                                                                                                                 Tel: [phone]  Fax: [phone]
                                                                                                                                 [e-mail]
January 9, 2015
Department of Homeland Security
USCIS Texas Service Center
P.O. Box 279030
Dallas, TX 75227-9030

Re.: EB1-A Petition for Permanent Residency under the category of Alien Worker of 
            Extraordinary Ability

           Petitioner/Beneficiary: Dr. XX
           Classification Sought: §203(b)(1)(A)
           Type of Petition: I-140