Vanilla One Block

All structure bounding boxes are kept, including custom structures
- Ocean ruins have a weird bug that cause some of the hitbox to generate at the bottom of the world
- All blocks in structures (generated in any step in or before underground_decoration) are removed
- All entities in structures (generated in any step in or before underground_decoration) are kept, meaning flying mobs will likely survive
  - In vanilla structures, non-flying mobs are not generated in most structures (exceptions being the ones that don't use structure files, e.g. ocean monument and ocean ruins)
- Structures can be added into the world by putting them in one of the steps in or after fluid_springs

Stronghold

The entire stronghold bounding box with the end portal in the same location as a normal world (for some reason the number of eyes are not consistent with a normal world)

The End

Exit end portals now generate at the correct height, matching the exact location it would generate in a normal world
There is some sort of bug involving some of the obsidian pillars and end crystals to not fully generate, but respawning the dragon will properly generate the pillarsMap

Map

In Jacobsjo's map, the snowy taiga markers will be hidden.

Terrain/Biome Datapacks

Datapacks that modify terrain using only density functions (e.g. tectonic, continents) are automatically compatible.

Datapacks that modify terrain via noise settings (e.g. terralith, lithosphere), modify biomes (e.g. nullscape, geophilic), or add custom biomes (e.g. incendium, terralith, nullscape) are not automatically compatible.

To add compatibility, an additional datapack can be created to patch/merge the changes between the two datapacks. There is a script in the source code to pull a datapack and create a compatibility pack. Compatibility packs have been added for Terralith, Nullscape, and Amplified Nether.