[
Edit] Sorry, I ended up repeating myself (I forgot that I already said most of this.) But there are some more concepts regarding sidelenght that you might find useful.
The callbacks will only be called when the voxel it is trying to access isn't in memory. Voxels aren't stored alone, but rather in memory blocks, often referred to as chunks.
The sidelenght is basically the amount of voxels it will store in a chunk, by default this is 32 voxels in a chunk. So when it tries to load a voxel at [10,10,10], and it isn't in memory, the callback will be called with the region of [0,0,0],[32,32,32] (where 32 == sidelenght). Your callback is in charge of (I haven't done this yet so I might be wrong) filling a chunk with the density/material values. This can be from disk, or a algorithm. It also works in the other direction too, when there are too many blocks in memory it calls the other callback (overflowhandler) for you to store the voxel data.
So yes and no, sidelenght influences when the callbacks are called, and how big a region they are in charge of filling with voxel data.
Quote:
Does this represent the max length of a size that can be in memory and not the maximum region?
Think I forgot to answer your actual question in my last post:
It decides the size of a chunk, but not the maximum amount of chunks that are loaded in memory.