Thebee, your explanation is very different from Scholj's. According to Scholj, people on the "under consideration" list are compared directly against the new interviewees. In other words, it's possible for the admissions committee to accept someone from the "under consideration" list over a newer interviewee.
According to you, they don't touch the "under consideration" list until they're finished interviewing (and presumably, offering all the spots they wanted to offer), and only take from the "uc" list if there are still empty spaces. A "pre-wait list", as you said.
So, which is it?
Their website, believe it or not, isn't particularly clear. It says:
"In order to manage the number of acceptances offered, the "under consideration" category is used as a temporary designation until your application is given a final designation.
As the admission season and interview process progresses (from October through April), we are able to utilize the "under consideration" category as needed.
In June, all applicants remaining in the "under consideration" category will be given final designations according to final cut-off scores. The "under consideration" category may ultimately result in an offer of acceptance, being placed on the alternate list, or not being accepted."
What I don't understand is this: how can they utilize the "uc" list as needed? Does "as needed" mean that a candidate in the "uc" list has a higher score than the best of the recent interviewees, and is offered admission over the newer interviewee? Clearly, when they say "in June, all applicants REMAINING in the 'uc' category will be given a final designation", they are indicating that 'uc' applicants are accepted prior to the end of the interview process.