What the heck's up with those things outside of level boundaries?

[PrismaticAngel]

What I'm talking about are these kind of things:

As you can see, there are alot of things outside the level boundaries. My question is: why exactly are they there? I also encountered an entire room of randomness, which is that big white bar outside the boundaries:

You can't see it, but the floor is constantly moving but it doesn't affect you.

Offtopic note: Before anyone goes blabbering how I got Super Tails here, I used FuriousFox's Super Monitor wad.

 

[Eblo]

Those are control sectors. They are often used for special effects concerning linedefs.

For more information:
http://wiki.srb2.org/wiki/Control_Sector

 

[PrismaticAngel]

But why are they outside the level then?

 

[Eblo]

But why are they outside the level then?

Usually for the reason of not interfering with the design of the part of the level that the player plays through. They can be in the level, but that often causes problems.

 

[BlueZero4]

Egg Rock has a bunch of wierd stuff that's not playable content but not technically "outside the map" either. It's not worth worrying over.

Control sectors are SRB2's way of including the extra information the game needs to know how to make the FOF. Things like heights, textures, and effects. They're really only important to the mappers anyhow.