Irrlicht Engine

Hey, so this is going to sound really dumb but can someone explain to me the prefixes in irrlicht source code.

Im pretty sure I can guess at what it means but I want to know for sure.
I-interface
E-enumeration
C-??

I notice some files don't get named with a prefix too.
What is the convention here?

C is class, S is struct or 'simple implementation', some files are simply helper function collections or other simple modules.

Thank you so much for your help. I feel stupid but this stuff is important if I want my code taken seriously.

Also, is it generally typical to name the classes with the prefix in front too.

Example,

class CSceneNode

yeah I've seen Irrlicht prefixes used somewhere else (also in other engines). I think irrlicht-style is really good idea. And yeah the prefix is usually used both in filename and in class/struct name. Why using different names that can create confusion? That way if you are searching for ISceneNode you need to look at ISceneNode.h.