Surface

The Surface constraint uses 3 groups:

Connection Set | Flags | Bounds | Filter | Pick Prompt
Group(0) | E3DOPGROUP_MAIN E3DOPGROUP_INPUTONLY | 1..1 | <undefined> | <undefined> (constrained input)
Group(1) | E3DOPGROUP_INPUTONLY | 1..1 | A Nurbs Surface Mesh with one surface | "NURBS Surface Mesh (1 Subsurface)" (constraining surface)
Group(2) | E3DOPGROUP_OUTPUTONLY | 1..1 | <undefined> | <undefined> (constrained output)

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