- Chunk Section: a 16×16×16 area, sometimes also called chunk.
- Chunk Column: 16 chunks aligned vertically (totalling 16×256×16).
A Chunk Section is defined in terms of other data types. A Chunk Section consists of the following fields:
|Field Name||Field Type||Notes|
|Bits Per Block||Unsigned Byte||How many bits per block in Data Array. If 0, the Palette Length and Palette fields are omitted and the global palette (with 13 bits per block) is used.|
|Palette Length||Optional VarInt||Length of the following array|
|Palette||Optional Array of VarInt||Mapping of block state IDs in the global palette to indices of this array|
|Data Array Length||VarInt||Number of bytes in the following array, divided by 8 (given as such because Notchian implements Data Array as an Array of Long)|
|Data Array||Byte Array||List of 4096 indices pointing to state IDs in the Palette, followed by padding to round the length up to the next multiple of 8 bytes|
|Block Light||Byte Array||Half byte per block|
|Sky Light||Optional Byte Array||Only if in the Overworld; half byte per block|
Data Array, Block Light, and Sky Light are given for each block with increasing x coordinates, within rows of increasing z coordinates, within layers of increasing y coordinates.
The global palette encodes a block as 13 bits. It uses the
minecraft:stone with damage
3) would be encoded as
In half-byte arrays, two values are packed into each byte. Even-indexed items are packed into the high bits, odd-indexed into the low bits.