according to my lawyer
most of RFE are just employeement prove on company letter head or pay stub.
but mine was special, look like they lost everything. so i have to give them everything including I-20, opt, h-1, 765 cards... and 5 year addresses, company letter 3 month pay stub, 3 year w-2...
The good thing is the more they ask for , the less they will read everything carefully.