Here is a picture showing my SSC file, the earthspec32k CTX file and the level folders for the earthspec32k virtual texture.
This picture includes some descriptions, too. It probably has too many arrows on it, but at least I didn't include lots of circles!
![Image](http://www.lns.cornell.edu/~seb/celestia/explain_spec.jpeg)
(this links to a much larger picture)
Celestia's window is in the background. It shows specular reflections on some of the tributaries of the Amazon River in Brazil.