You can move the vertices on a polygon along the direction of their normal.
To move polygon vertices along their normals
For example, if you revolve a curve to create a surface, then tweak CV number 3 on the surface, the tweak will always apply to CV number 3. If you later change the revolve node attributes to reduce the number of segments on the surface, the CV that you tweaked will now have a new number, and the tweak will no longer be applied to it. The tweak will be applied to the CV that is now number 3, which may be in a different location on the surface.