My category is EB2. The RFE was about previous employer's address and updated contact info. Since the employment letter i submitted had old address and old phone number. The company has moved. BCIS might have tried to reach them and could not find a company and so they asked for updated...
It should say something like this.
Receipt Number: WAC0320xxxxxx
Application Type: I140, IMMIGRANT PETITION FOR ALIEN WORKER
On August 7, 2003, we received your response to our request for evidence or information. It is taking between 158 and 60 days for us...