huh.. so you have to meet middle band requirement to be considered for second round and third round offers? =/
Nope, you are getting confused now. Middle-band offers are made in first round offers too.
When the course decides to allocate places to their applicants, they set aside a certain number for the middle-band. They look at people who did not quite make the clearly-in, but did particularly well in the pre-requisite subjects. Once they have made the decision which applicants will get offers, they post this up, and these are the first-round offers.
Applicants with offers can either accept the offer, reject it, or defer it. The ones that are rejected and deferred open up new spots for the course. This initiates a second round, where new spots are allocated to applicants next in line. This cycle continues until all the spots of the course are given out (or until they can't be fucked).