While helping someone debug odd biomes showing up in the overworld when they should not, a strange behavior of vanilla biome placement was found.
Any time Vanilla is placing a biome down, numbered 0 to 127, if there is a valid biome at n+128, then that biome can be used as a sub biome.
It is not just limited to the vanilla biomes (0-39) claiming 128-167; ANY mod added biome in 168-255 can be found as a sub-biome of another.
This has good and bad news. The good is that you can get user defined sub-biomes. The bad is that there are much fewer effective biome slots.
Again: The only safe place for mod-added biomes in 1710 is 40 to 127.
Any time Vanilla is placing a biome down, numbered 0 to 127, if there is a valid biome at n+128, then that biome can be used as a sub biome.
It is not just limited to the vanilla biomes (0-39) claiming 128-167; ANY mod added biome in 168-255 can be found as a sub-biome of another.
This has good and bad news. The good is that you can get user defined sub-biomes. The bad is that there are much fewer effective biome slots.
Again: The only safe place for mod-added biomes in 1710 is 40 to 127.