Switches between the top-down and bottom-up geometry selection modes.
When the selection mode is set to top-down, the selection sequence begins at the top-most level and ends with the elemental geometry. When the selection mode is set to bottom-up, the selection begins with the elemental geometry.
When the selection order is set to bottom-up, the first click selects the geometry, the next click selects the part, the next click selects the subassembly, and the next click selects the next higher level assembly, and so on until the top-level assembly is selected. A tooltip (not shown in the image) displays the name of the object selected, as you click.
When the selection order is set to top-down, the first click selects the top-level assembly, the next click selects the next level of a subassembly, and so on until the geometry is selected. A tooltip (not shown in the image) displays the name of the object selected, as you click.