The purpose of MVC is to separate UI from domain logic. In doing so, an MVC implementation typically develops a set of reusable classes for each of the concerns in the triad. Sometimes, data or behavior that firmly belongs on the user interface side of the division can conveniently be represented using the infrastructure of the model side of the division. Thus objects that would appear at first glance to be in the model are really part of the interface concern, that is the view and controller.
Some examples include scrollbar positions and column sorting.
This is sometimes called an Application Model and the pattern known as MMVC after the idea that there are two separate models.
