Correct, there were TWO types of admissions back in the day. Normal admission got you into the exhibits/fly mart. To get through the arch, or south on Wittman road past the red barn, you had to have a "flight line" pass which either meant you were a pilot, a member of the EAA or some other pilot group (like AOPA), or otherwise approved.

Of course, I remember back when you had to indicate to AOPA that you were either at least a STUDENT pilot or an aircraft owner to join as well.