This model visualizes a planar rectangle. The center of the rectangle is located at connector frame_a (visualized by the red coordinate system in the figure below). The figure below shows two rectangles of the same parameters
nu = 8, nv = 3, length_u = 3, length_v = 2.
The green rectangle on the right is visualized in wireframe thus highlighting the influence of the discretization. Moreover, the u-axis of this rectangle is modified so that the rectangle is rotated about the z-axis of frame_a.