It is your option, not required by USCIS.

来源: 2009-12-28 18:10:01 [博客] [旧帖] [给我悄悄话] 本文已被阅读:
You can provide any documents you think it is necessary, but it does not mean USCIS require you to do that. For immigration events, we usually only need to provide what the USCIS wants and we do not need speculation what we need to do.