Some times you need to select nodes only on the surface of the mesh. This can be done when the mesh is displayed in the surface mode (see ”Toggle Surfaces/Volumes”) using the menu-entry ”Show Elements With Light”. To find node positions more easily add the element edges to the view (see Toggle Element Edges).
How to select only nodes on the surface
A different way uses the element-faces (see ”plot” with parameter ”f”). Store the desired faces in a new set (qadd) and complete the set downwards (“comp set do”). Check the selected nodes with “plot n setname”. Or you add all faces at once in a new set with “seta surfs f all” before completing the set downwards.