The relationship between distribution levels (contour lines/zones) and the Chart3DContourStyles collection is as follows: if nstyles contour styles are provided, and the number of distribution levels is nlevels, the index of the contour style associated with the nth distribution level is the largest integer less than or equal to the following:

To modify the Contour Levels through the Chart3DContourLevel Collection Editor:

1. In the Properties window, expand the ChartGroups node.
2. Press the ellipsis next to ChartGroupsCollection to display the Chart3DGroup Collection Editor.
3. Expand the Contour node.
4. Press the ellipsis next to Levels to display the Chart3DContourLevel Collection Editor.
   
5. Add, remove, or modify levels as desired. For more information, see Contour Style Appearance Properties.