分享点信息。
我的ＣＡＳＥ是在ＮＳＣ，是２００２年１０月ＦＩＬＥ的Ｉ４８５，是ＥＢ３。已经按了两次手印。现在收到Ｉ７９７Ｃ要做biometrics。是ＣＯＤＥ ２。我问了我的律师。这是他的答复（英文部分）：
Code 2 is to check birth date/country and parentage. Applicants are required to go through this before approval of green card, at times, even after approval but before issue of actual card. I believe your case will be approved soon after the code 2 fingerprinting and security name check.
我理解ＣＯＤＥ ２是thumbprint, digital photo, and signature. 但愿如律师所说。