I did a lot of web surfing to answer this question recently and I found that while there is a lot of confusion, the control No. comes up as the winner. I cross checked with a lawyer-filed I-485 (famous lady lawyer in MD) and found its the control number thats entered in the box asking for Nonimmigrant visa #, usually begins with a year like 2001.....It might be worth confirming with a lawyer.
silent.