I'm not sure if this is what those terms mean, since I've never heard them before, but at my school they offer a limited number of students the opportunity to take the majority of their core clerkships (Surgery, Family, EM, Peds, Ob/Gyn, and their SubI) attached to a rural family practice clinic and occasionally at a nearby local community hospital. The Peds, Ob, and Family are all mixed together in the family practice enviornment with one or two days a week at the local hospital to focus on EM and Surgery. This is as opposed to normal students to take their clerkship one specialty at a time at major medical centers. I would guess that's what your school is refering to?
The simplest way to find out, of course, would be to ask them directly.