• A surface can be one patch, or it can be composite.

• To create a surface, use two or more chains. A chain is composed of curves or edges with tangent continuity between them.

• The defining chains of a surface must have soft point connections, or they must share vertices at the endpoints where they intersect.

• You can select and trim primary chains or internal curves of a composite surface for defining a surface.

• To further define surface shape, you can add internal curves to boundary surfaces and cross curves to sweep surfaces.

• Use reparameterization curves to shape boundary or loft surfaces when you create or redefine them.

• You can convert a boundary surface into a trimmed rectangle surface and vice versa.

• When you make a composite surface into a trimmed rectangle surface, one patch surface is created. You can use automatic curve connections to define the surface.