"thumb" printing and photographs

[sandeepsharma7]

I made a case status inquiry on my marriage based i-485 (pending since feb05) on 1-800 number and received a letter stating that case has been approved and file has been sent for card production but it's not an official approval notice. I received this letter a month ago, I then went to local office for follow up, they said that the thumb printing plus photographs have not been taken yet. Officer said that he will have "thumb printing" notice sent to me in a week and then I will have to get it done at local office. After that, I will receive the card or can get i-551 stamped.
I am wondering what exactly is this "thumb" printing (not the regular fingureprinting) and if this is a usual process?

 

[ginnu]

I made a case status inquiry on my marriage based i-485 (pending since feb05) on 1-800 number and received a letter stating that case has been approved and file has been sent for card production but it's not an official approval notice. I received this letter a month ago, I then went to local office for follow up, they said that the thumb printing plus photographs have not been taken yet. Officer said that he will have "thumb printing" notice sent to me in a week and then I will have to get it done at local office.

After that, I will receive the card or can get i-551 stamped.

I am wondering what exactly is this "thumb" printing (not the regular fingureprinting) and if this is a usual process?
------For GC production they take your thumb immpression, signature on white form (I think it is I-181) 2 photographs and then send it to service center and then card production unit makes the card. when you go to local office for take 2 photographs front facing(passport photo)

 

[sandeepsharma7]

I thought USCIS gets the thumb impression from the fingureprinting/biometrics, I am not sure why the guy told me send a notice to come in for thumb impression. weird.