Preset code format
At a future point there is expected to be some way of choosing block types merely by selecting them from a menu. For now, you must type in a correctly-formatted preset code.
The code is a string of numbers, semicolons, colons, commas, and lowercase "x"s. Each code has three main parts, divided by semicolons: a version number (used to allow preset codes to be shared even if the code format changes), a block mask, and a biome ID. The block mask is a comma-separated list of block IDs, ordered from layer 0 up; if the entry for a given block has an "x", the number before the "x" is the number of layers to be generated, and the number after is the block ID. A block ID can be followed by a colon to specify a damage value.
Structure generation specifiers (described below) can have parameters, for example "village(size=0 distance=0)".
"village" means it can generate a village. Parameters are "size", for the size of the village (0 = default, 1 = superflat default) and "distance", for the distance between villages.
"mineshaft" means it can generate a mineshaft, even in midair. A "chance" parameter from 0.0 to 1.0 determines how common mineshafts are. Note that 1.0 will result in several mineshafts layered into each other, and is likely to also cause a lot of lag when generating.
"stronghold" means it can generate a stronghold. The "count" parameter determines how many exist per world.
"biome_" followed by a number is the type of biome the whole map will spawn at. For example, "1" is the plains biome.
"dungeon" means it can generate dungeons.
"decoration" means it generates trees, tall grass, flowers, pumpkins, etc. according to the biome. Also populates stone layers with ores according to depth.
"lake" means it generates water lakes, with sand and sugar canes depending on biome.
"lava_lake" means it generates lava lakes.
For example, consider the preset code 1;48,250x0,49,78:2;8
It consists of the following elements:
1 – version number.
48,250x0,49,78:2 – comma-separated list of block IDs.
48 – one layer of Mossy Cobblestone on layer 0.
250x0 – 250 layers of air, from layer 1 to layer 250.
49 – one layer of obsidian, on layer 251.
78:2 – one layer of thicker-than-usual snow, on layer 252.
8 – biome ID, in this case Nether.
A block can also be repeated over multiple layers simply by repeating the block's ID, e.g. 20,20,20,20 would give the same result as 4x20.
The Player will spawn on the topmost solid layer, and will spawn under water or lava if there are layers of those above the topmost solid layer.
Attempting to use an incorrectly formatted preset code causes the game to default to the Classic preset.