One input

When only the surface is specified, it must contain at least one profile in order for Curveclay to work. In this case, you must specify how the surface should be deformed in the region near the profile (whether to deform the profile along a vector \[X, Y, Z or User Defined], or along the surface normal). You must also specify how far out the surface should be pulled, using the Distance parameter.

When one or more profiles form a closed loop, you have the option to displace the inside of the loop, by enabling the option Deform Inside of Loop. Another option allows you to form a closed loop by using several open profiles. The algorithm is the same as the one used in the Trim SOP when not treating curves individually. This might be useful for putting a regular dent into a surface (e.g. A circle, or a font).

Two inputs

When the surface and a set of deforming faces is specified (the deformed faces are the third input) the profiles on the surface will be snapped to the deforming faces. This option has no additional inputs. This might be useful when you want to snap any profile to any free floating curve.

Three inputs

When all three inputs are specified, the Rest faces will first be projected to the surface. The projection is done in two ways: along a specific vector (X, Y, Z, or User Defined) or along the Minimum Distance to the surface. Each point on the curve will first be projected to the surface. Then this curve will not be snapped to the deforming face. Rather, the curve will be deformed by the difference between the rest face and the deforming face. This option provides flexibility on all inputs. For example, this would be ideal for creating random mountain ranges.