Deselects every nth vertex (where n = Gap value + 1) along a selected and indicated path.
Every other vertex is selected if a Gap of 1 is specified. Every third vertex would be selected if a gap of two was specified. Etc.
An example use of Deselect on Path is to create a "gear" shape.
1. Make a circle. Make sure that it doesn't have a vertex in the center.
2. Select the circle and indicate one of the vertices.
2. Choose the Deselect on Path command and a Gap value of 1.
3. Notice that every other vertex is now deselected.
4. Double-click on the scale tool.
5. Resize them larger or smaller, but make sure that the "From Center" option is selected, not "From Cursor".
6. Extrude the "gear" type shape to create the gear.