Hey there, 

when I implement a Coupling Constraint in Abaqus CAE, I get to chose between a Node Region or a Surface (equals an element based surface) as coupling options. In the Simulia Assistant it is stated: "

The surface-based coupling constraint couples the motion of a collection of nodes on a surface to the motion of a reference node."

Why do I get different results for the two types of region when obviously by selecting an element-based surface as coupled region, only the nodes of that surface are selected. Which again should equal chosing a node set directly. Where's the mistake?