What are flags and how do I use them?

I have searched these forums but people already seem to know what they are, and nobody has mentioned how to actually use them. I want to be able to do something like warping to a warp, then that second warp will turn a flag on and put you in another area, and you will have to exit and load the level again and be where the second warp is but not warp. Like this:

Use warp A: Warp to B, save.
Collision with Warp B & flag off: Warp somewhere, set flag on.

Is this possible somehow? I would really like an explanation of what flags are and how they are used.

Thanks,
-LB

I've [search]ed a bit, and after a mention in the [faq] I noticed a link to this topic: http://nifflas.lpchip.nl/index.php?topic=20.0

OK, I have read that, but I am still somewhat confused. Do they instantly teleport you from that room, or do they only apply to warps?? I've done some testing but it just doesn't make any sense!

When you enter a screen with a flag on, it looks for a flag warp. If there is one, it warps you the number of screens the flag warp tells you to. Also, flag warps have nothing to do with regular warps and don't require the orange arrow square object.

EDIT: Here, take the flag demonstration level I made, and look at the settings ini. (Level > Settings in the menu bar) It should be simple enough.

Ahh, thanks! I think I understand it much better now. So what I want to do is possible.

Glad to hear I could help.