THe example is in the update manual, basically its on by default and can be disabled by changing chunk size to "0", example "var terrain_chunk = 0;" or if left on meaning chunk size is set to a value from "1" to "256" can be told to ignore specific terrain files by changing the file name of the terrain to end with "_" or "_n", example "terrainR1C3_n.hmp". There are consiquences like mesh deformation is disabled when chunked.