This one is both undocumented and unsupported, so don’t ask me any details.
A user on the Civil 3D newsgroup wanted to know how to find object layers easily. Dan Philbrick (of the Friday Dan & Dave show fame…) mentioned a command called AecInspect. This gives object information, as well as object layer information. It won’t get subcomponents, but could prove to be quite useful from time to time.
Here’s a sample result of a report on a surface that I have: