A Ribbon surface is a datum that represents a tangent field created along a base curve. The Ribbon surface is tangent to reference curves that intersect the base curve.

You can use a Ribbon surface to impose tangency conditions between two surface features. With the Ribbon surface you can define the patch structure so that adjacent surfaces can be made tangent to each other without using one of them as a tangent reference. In this way, the Ribbon surface acts a tangent reference. Using this method, you first create the Ribbon surface. Then you can create each surface and make it tangent to the Ribbon surface. After you have created tangency between two adjacent surfaces, you can put the Ribbon surface on a layer and blank it.

You can predefine a layer for ribbon surfaces. To do this, specify the name for the layer using the def_layer (layer_ribbon_feat) configuration option. Each time you create a ribbon surface, the system automatically adds it to this layer.