The window "Domain" displays a domain as a wireframe, a point (u0, v0) in the domain, and the u-constant and v-constant curves through that point in red and green, respectively.

The window "Surface X(u,v)" shows the parametrized surface for the given domain and the images of the point and the curves from the "Domain" window. Note that in this case, since X(u,v) = (u,v,f(u,v)), the surface is the graph of f(u,v), and the images of the curves shown in the "Domain" window are the x-constant and y-constant slices of the graph.

It is possible to change u0, v0, and f(u,v) in the control window.