Alright, have you ever ran into the problem of your level being too long? Well, here's the steps to making a clean split into parts for your level without recreating anything!
First, take your level code. Make one extra copy for every segment you want your level to take up. (i.e. if you want to split it into two parts, make two copies. And so on and so forth.) Save these in two code boxes in one PM or two save files in notepad, whichever you prefer. They simply must be the same code duplicated.
Now view this diagram below. This is the example of level 2 of my Such Great Heights level.
This is the basic graph of that level. But say I wanted to split it so that there was one level from mine to flying course, and then from from sky to the end.
There's a tool you use for resizing levels- it's in course info. What you can do is instead of adding more to the level, subtract it.
So take the first code, go to the far edge of where you want the level to end. In this case the flying course.
So I want my level to look like this. I go to the far right of the flying course and then from the far right side of the Course Info size graph I press minimize. I hold down minimize until the end of the course is at the far right of the flying course, where I want to end this first level. The parts you don't want in this level are thereby deleted. Which is why it's important to have a second code.
Be careful, though, as it is possible to minimize a bit too much. If this happens, you can either do some reconstruction or load in the code and try again.
Once you've finished resizing to your specs, save the new code somewhere and rejoice, because now you have the first half of your level done!
Now to the second half.
Now this is basically the same as the first, but this time, you're going to the far left of the sky and minimizing from the far left, thereby erasing the mine, snow, and flying course. That's all there is too it. Then save the code with the first half and voila! You have split your level in half!
Now if you want to split into thirds, it's almost as easy. You do the far sides like stated above, and then for the middle, you minimize from the left and the right. Simple as that.
So that's MoD's guide to splitting your level into pieces! Hope you find this useful! And I hope I'm not repeating what you already know!