Java Edition 18w06a

18w06a is the seventeenth snapshot released for Java Edition 1.13, which mostly added two new air variants, added new biomes for the End, re-added, added a furnace recipe book, and removed the Customized world type, as well as the rewrite of the world generation system as a result.

Blocks
Added  and.
 * Air
 * Both have the exact same properties as regular air.
 * generates in caves.
 * is used internally for blocks above (>= 256) and below (< 0) the world, and in unloaded chunks.

World generation

 * Biomes
 * Added  (The End - Floating Islands),   (The End - Medium island),   (The End - High island), and   (The End - Barren island).

Command format

 * Re-added the command into the game.
 * Re-added the command into the game.


 * Entity selectors
 * Added command suggestions for entity selectors.

General

 * Recipe book
 * Recipe book icon now is a separate file, it's stored in the.
 * Added a recipe book for the furnace.
 * Furnace recipes have been moved to JSON files.
 * They use.
 * is used to determine the time it should take to smelt an item in the furnace.
 * is used to determine the amount of experience a player should get when picking the resulting item out of the furnace manually.
 * Fuel is not included and is still hardcoded.
 * "Unlocked recipe" toasts now show an icon in the top left to specify whether the unlocked recipe is a crafting or smelting recipe.


 * Tags
 * Added new vanilla block tags:
 * ,,  , and.
 * Added new vanilla items tags:
 * ,,  ,  , and.

World generation

 * General
 * Rewrote the world generation system.
 * Structures previously grouped under "Temple" have their spawning locations changed, this allowed to differentiate between the structures.
 * In the Nether, vertical air cavities — stretching from bedrock level to as far as Y=35, and filled with lava from bedrock level to Y=10 – now occur in chains across the bottom of the Nether, often forming extensive ravines.


 * Customized world type
 * Removed from the game.
 * Will be re-added in the future.


 * Trees
 * Large spruce trees now transform nearby grass blocks into podzol when they grow.
 * Trees sometimes generate upside down for an unknown reason.

Command format

 * General
 * Whitespaces are now allowed in entity selectors & blockstate arguments.


 * Now accepts different structure names for all structures previously grouped under.
 * ,,  , and.
 * ,,  , and.

Video
Video made by slicedlime:

Trivia

 * Unlike most of the first-of-the-week snapshots, this was released on a Friday instead of Wednesday.