Ok I thought I would come to the sourse for an answer to this question.

I like to discect rooms to find out how they are put together (after making a backup of-course) like how certain objects are used and such like, I have come across an object that has me beat and that is "black plane" objects. They must have something to do with sky because they are always found high above rooms. What do these object do if anything and are they an essential part of a room (as not all rooms have them), as I am trying to learn about modding the game all the info I can get will be helpful.

For some reason, reading you post made me think of http://www.youtube.com/watch?v=w2yv8aT0UFc.

Jokes aside, This is not the modding forums.

Click on "Bethesda Softworks Forums"
Click "The Elder Scrolls"
Find the Elder Scrolls game you are modding and go to the Construction Set or Creation Kit forum for that game.
Hopefully you'll get your answers there.

Good luck...

Now moved. Thanks mods.

They hide the Map of the dungeon to appear ...

Yes if these are what I'm thinking of, they've used these since Morrowind to hide messy bits that they don't want appearing on the local map.

Yep. Though in MW they were also good for blocking off holes making it appear dark "inside/outside". Skyrim doesn't need this since interior space is black by default.

you can also use them to prevent visible void space (or unwanted visible geometry) for custom load doors

Actually Interior space has a Skybox by default, so you'd need to block off any holes. Unless it's intentional. (Like a whole in a cave ceiling)

And yes, whatever they are over doesn't show up on the Local Map. You'll notice most of the caves in the game look like they have sharp edges, which they don't at all, the dev just lines up some black planes to block off the muttled mess that makes up the crazy and unique cave designs.

It doesn't for me..I should probably check up those settings.

Oh I think there is a checkbox somewhere that says 'Show Sky' or something like that. It's probably off by default, I just always copy Beth cells and like 99% of them have it turned on.