[OR] Overlay/stripping components properties

Does anyone have a demo of the use of overlay and stripping? If it was as simple as "overlay" and "stripping", we would have two settings in the component properties window. Instead, we have several options.

I know from a provided example that for milling, you want to have the top follow the active surface and the bottom follow the component (as constructed in the template). (Actually, in the example I'm basing this on, it is not a stripping component. I'm not convinced that it matters whether that is toggled on or not.)

I know similarly that for leveling, you want to have the top follow the component and the bottom follow the lowest element (milling, because practically speaking, milling will be the lowest element). (But I misunderstood "Lowest" as I came to this conclusion. Component works just as well for this purpose, in conjunction with the milling component above.)

But there are other options, such as that the top follows the highest, and that the bottom might follow the highest or the surface.

So, partly what I'm confused about is that using any other combination of settings will either do nothing or do something that I can't predict prior to testing. So, I went hunting for the documentation, which I went through the file explorer to find. (The file is at c:\Program Files (x86)\Bentley\PowerGeopak v8i (SELECTseries)\Documentation\geopak_corridormodeling.chm. The article is under Corridor Modeling > Open Create Template > Properties > Component Properties.) 

Top Option specifies how the top of the component is defined.

• Follow Component specifies the top of the component will follow the defined top of the component.
• Follow Surface specifies the top of the component will follow the surface (which does not support aliasing).
• Follow Highest specifies the top of the component will follow the highest of the component or surface.
  • In other words, MAX(component, surface). Without looking at the documentation, "Highest" suggests MAX(surface, set of all components)

Bottom Option specifies how the bottom of the component is defined. The behavior of these options can be different, depending on the selected Top Option.

• Follow Component specifies the bottom of the component will follow the defined top of the component at the defined depth, but will not go above the top of the component.
  • What, again? It follows the top of the component but will not go above the top of the component? Surely I'm missing something, but what?
• Follow Surface specifies the bottom of the component will follow the surface at the defined depth, but will not cross over the top of the component.
• Follow Lowest specifies the bottom of the component will follow the lowest of the component or surface at the defined depths.
  • In other words, MIN(component, surface) - depth. As noted above, "Lowest" suggests MIN(surface, set of all components) - surface depth.
• Follow Highest specifies the bottom of the component will follow the highest of the component or surface at the defined depths.
  • In other words, MAX(component, surface) - depth.

What if we want to target a specific component or set of components instead? Or even "Design" as we have that option for point constraints.

In any case, I haven't formed a really solid question around this, but I'm sensing a certain vagueness about the distinction between component depth and surface depth, and the bottom surface of a stripping element seems to be inaccessible to other points in the template.

Does anyone have any advice on how to use all these?

I see Alternate Bottom Surface. This seems to have no function whatsoever. Under what constellation of settings does this do anything? What if I want to use an alternate top surface?