Checkpoints and Borders Policy Debate - The backside on form I94

Upon entering the United States all foreigners with a non immigrant visa (with a few exceptions) are given a white form called I94. When you look on the backpage (sample here: http://forms.cbp.gov/pdf/arrival.pdf) you will see this side for government use only with primary and secondary inspection. What I am wondering about is what all the codes under reason referred means like 212A, PP, Parole etc on the back side? Is this side only used when you have to go through a secondary inspection?

212A I would hazard a guess refers to the Immigration & Nationality Act 212 part (a) which deals with reasons of ineligibility for entry: http://www.uscis.gov/ilink/docView/SLB/HTML/SLB/0-0-0-1/0-0-0-29/0-0-0-2006.html

Parole will probably be something to do with that lovely term called advanced parole.

No idea regarding the rest.

When I was a student, the officer always had to write some information from my I-20 form such as the Program Number and Name of the University.

When I was a student, the officer always had to write some information from my I-20 form such as the Program Number and Name of the University.

I've had everything between nothing and SEVIS number, school name and location.

SEVIS is where all international students and their dependents are registered (not sure if they got more people in there too)