Confused

[Kevin F]

This sounds like a newby question but how and why do some projects have "hidden! nodes within nodes. The Planets pack for instance has examples of this i.e. the "See inside rock obj for multi rings". It must be that this topic has been mentioned and explained before but I obviously missed it. I seem to manage quite well  without it but I'm wondering if I'm missing out on something vital for expert use of the program.
The planets pack is really nice by the way -thank you PS. A tutorial explaining how it was made and why certain values/function were used would be very useful.
I know your busy right now but sometime in the future it would be appreciated.

[cyphyr]

The planets pack is by FrankB so he should get the credit
Most nodes (if not all?) have an internal structure, mostly empty, but its a usefull place to keep extra complex node structures, stops them cluttering up the workspace. Plugging stuff into the internal structure is the same as plugging it into the nodes input (or child in the case of surface layers) Nothing differant is happening here, its just for convience really
richard

[rcallicotte]

Like cyphyr explained, it's a convenience.  As I understand it, it helps to keep the node structures neater.