Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.13.2, protocol 404) to the current pre-release (currently 19w08a, protocol 461). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.

Contents

Data types

Position

64-bit value split in to three parts

• x: 26 MSBs
• z: 26 LSBs middle bits
• y: 12 bits between them LSBs

Encoded as followed:

((x & 0x3FFFFFF) << 38) | ((y & 0xFFF) << 26) | (z & 0x3FFFFFF) ((z & 0x3FFFFFF) << 12) | (y & 0xFFF)

And decoded as:

val = read_unsigned_long();
x = val >> 38;
y = (val >> 26) & 0xFFF val & 0xFFF;
z = val << 38 >> 38 (val << 38 >> 38) >> 12;

Note: The details of bit shifting are rather language dependent; the above may work in Java but probably won't in other languages without some tweaking. In particular, you will usually receive positive numbers even if the actual coordinates are negative. This can be fixed by adding something like the following:

if x >= 2^25 { x -= 2^26 }
if y >= 2^11 { y -= 2^12 }
if z >= 2^25 { z -= 2^26 }

Packets

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre
Play clientbound
0x00	Spawn Object	Current	Pre
0x09	Update Block Entity	Current	Pre
0x14	Open Horse Window		Pre
0x22	Chunk Data	Current	Pre
0x26	Map Data	Current	Pre
0x2C	Open Book		Pre
0x2C 0x2D	Open Sign Editor	Current	(unchanged)
0x2D 0x2E	Craft Recipe Response	Current	(unchanged)
0x2E 0x2F	Player Abilities (clientbound)	Current	(unchanged)
0x2F 0x30	Combat Event	Current	(unchanged)
0x30 0x31	Player List Item	Current	(unchanged)
0x31 0x32	Face Player	Current	(unchanged)
0x32 0x33	Player Position And Look (clientbound)	Current	(unchanged)
0x33	Use Bed	Current
0x4E	Entity Sound Effect		Pre
0x4E 0x5F	Player List Header And Footer	Current	(unchanged)
0x4F 0x50	Collect Item	Current	(unchanged)
0x50 0x51	Entity Teleport	Current	(unchanged)
0x51 0x52	Advancements	Current	(unchanged)
0x52 0x53	Entity Properties	Current	(unchanged)
0x53 0x54	Entity Effect	Current	(unchanged)
0x54 0x55	Declare Recipes	Current	Pre
0x55 0x56	Tags	Current	Pre
0x57	Update Light		Pre
0x14 0x58	Open Window	Current	Pre
0x59	Trade List		Pre
Play serverbound
0x1B	Recipe Book Data	Current	Pre
0x29	Player Block Placement	Current	Pre

New/modified data types

No changes so far.

Entity Metadata

Entity Metadata Format

Note that entity metadata is a totally distinct concept from block metadata. It is not required to send all metadata fields, or even any metadata fields, so long as the terminating entry is correctly sent.

Entity Metadata is an array of entries, each of which looks like the following:

Name	Type	Meaning
Index	Unsigned Byte	Unique index key determining the meaning of the following value, see the table below. If this is 0xff then the it is the end of the Entity Metadata array and no more is read.
Type	Optional VarInt Enum	Only if Index is not 0xff; the type of the index, see the table below
Value	Optional value of Type	Only if Index is not 0xff: the value of the metadata field

Value of Type field	Type of Value field	Notes
0	Byte
1	VarInt
2	Float
3	String
4	Chat
5	OptChat (Boolean + Optional Chat)	Chat is present if the Boolean is set to true
6	Slot
7	Boolean
8	Rotation	3 floats: rotation on x, rotation on y, rotation on z
9	Position
10	OptPosition (Boolean + Optional Position)	Position is present if the Boolean is set to true
11	Direction (VarInt)	(Down = 0, Up = 1, North = 2, South = 3, West = 4, East = 5)
12	OptUUID (Boolean + Optional UUID)	UUID is present if the Boolean is set to true
13	OptBlockID (VarInt)	0 for absent otherwise, id << 4 | data
14	NBT
15	Particle
16	Villager Data	3 VarInts: villager type, villager profession, level
17	OptVarInt	0 for absent; 1 + actual value otherwise. Used for entity IDs.
18	Pose	A VarInt enum: 0: STANDING, 1: FALL_FLYING, 2: SLEEPING, 3: SWIMMING, 4: SPIN_ATTACK, 5: SNEAKING, 6: DYING

Villager type (minecraft:villager_type registry):

Name	ID
minecraft:desert	0
minecraft:jungle	1
minecraft:plains	2
minecraft:savanna	3
minecraft:snow	4
minecraft:swamp	5
minecraft:taiga	6

Villager professions (minecraft:villager_profession registry):

Name	ID
minecraft:none	0
minecraft:armorer	1
minecraft:butcher	2
minecraft:cartographer	3
minecraft:cleric	4
minecraft:farmer	5
minecraft:fisherman	6
minecraft:fletcher	7
minecraft:leatherworker	8
minecraft:librarian	9
minecraft:mason	10
minecraft:nitwit	11
minecraft:shepherd	12
minecraft:toolsmith	13
minecraft:weaponsmith	14

Mobs

Entity IDs have shifted with the addition of some new mobs.

Entity

The base class.

Ids have not been updated to account for the massive shift due to addition of new metadata in classes high up the hierarchy

Index	Type	Meaning		Default
0	Byte	Bit mask	Meaning	0
		0x01	On Fire
		0x02	Crouched
		0x04	Unused (previously riding)
		0x08	Sprinting
		0x10	Swimming
		0x20	Invisible
		0x40	Glowing effect
		0x80	Flying with elytra
1	VarInt	Air		300
2	OptChat	Custom name		empty
3	Boolean	Is custom name visible		false
4	Boolean	Is silent		false
5	Boolean	No gravity		false
6	Pose	Pose		STANDING

Itemed Throwable

Extends Throwable.

Used for all things that previously extended throwable other than potions, which already had an item.

Index	Type	Meaning		Default
6	Slot	Item		empty (which behaves as if it were a specific item, depending on the subclass)

Egg

Extends Throwable.

No additional metadata.

An empty item behaves as if the item were a minecraft:egg.

Ender Pearl

Extends Throwable.

No additional metadata.

An empty item behaves as if the item were a minecraft:ender_pearl.

Experience Bottle

Extends Throwable.

No additional metadata.

minecraft:experience_bottle

Snowball

Extends Throwable.

No additional metadata.

minecraft:snowball

Eye of Ender

Extends Entity.

Index	Type	Meaning		Default
6	Slot	Item		empty (which behaves as if it were a minecraft:ender_eye)

Arrow

Extends Entity.

Abstract base class for TippedArrow (which is used for regular arrows as well as tipped ones) and Spectral Arrow.

Index	Type	Meaning		Default
6	Byte	Bit mask	Meaning	0
		0x01	Is critical
		0x02	Is noclip (used by loyalty tridents when returning)
7	OptUUID	Shooter UUID		Empty
8	Byte	Piercing level		0

TippedArrow

Extends Arrow.

Used for both tipped and regular arrows. If not tipped, then color is set to -1 and no tipped arrow particles are used.

Index	Type	Meaning		Default
8 9	VarInt	Color (-1 for no particles)		-1

Trident

Extends Arrow.

Index	Type	Meaning		Default
8 9	VarInt	Loyalty level (enchantment)		0

Itemed Fireball

Extends Entity.

Used for regular and small fireballs. Not used for dragon fireballs and wither skulls. Interestingly, regular fireballs do not come from an item.

Index	Type	Meaning		Default
6	Slot	Item		empty (which behaves as if it were a minecraft:fire_charge)

Fireball

Extends Abstract Fireball Itemed Fireball. This is the large fireball shot by ghasts.

No additional metadata.

Small Fireball

Extends Abstract Fireball Itemed Fireball. This is the fireball shot by blazes and dispensers with fire charges.

No additional metadata.

Fireworks

Extends Entity.

Index	Type	Meaning		Default
6	Slot	Firework info		empty
7	VarInt OptVarInt	Entity ID of entity which used firework (for elytra boosting)		0
8	Boolean	Shot at angle (from a crossbow)		false

Living

Extends Entity.

Index	Type	Meaning		Default
6	Byte	Hand states, used to trigger blocking/eating/drinking animation.		0
		Bit mask	Meaning
		0x01	Is hand active
		0x02	Active hand (0 = main hand, 1 = offhand)
		0x04	In riptide spin attack
7	Float	Health		1.0
8	VarInt	Potion effect color (or 0 if there is no effect)		0
9	Boolean	Is potion effect ambient: reduces the number of particles generated by potions to 1/5 the normal amount		false
10	VarInt	Number of arrows in entity		0
12	OptBlockPos	Unknown (Bed location?)		Absent

Ravager

Extends Monster

No additional metadata.

Status	Description
4	Starts the attack animation.
39	Starts the stun animation.

Panda

Extends Animal.

Index	Type	Meaning		Default
13	Integer	Breed timer? Set to 32 when something happens, and then counts down to 0 again. At 29 and 14 (before counting down), will play the entity.panda.cant_breed sound event.		0
14	Integer	Sneeze timer. Counts up from 0; when it hits 1 the entity.panda.pre_sneeze event plays and when it hits 21 the entity.panda.sneeze event plays (and it is set back to 0 and the sneeze flag is cleared).		0
15	Integer	Eat timer. If nonzero, counts upwards.		0
16	Byte	Main Gene		0
17	Byte	Hidden Gene		0
18	Byte	Bit mask	Meaning	0
		0x01	Unused
		0x02	Is sneezing
		0x04	Is eating
		0x08	Unknown
		0x10	Unknown

Fox

Extends Animal.

Index	Type	Meaning		Default
13	VarInt	Type (0: red, 1: snow)		0 (red)
14	Byte	Bit mask	Meaning	0
		0x01	Sitting
		0x02	Unused
		0x04	Crouching
		0x08	Unknown
		0x10	Unknown
		0x20	Sleeping
		0x40	Unknown
		0x80	Unknown
15	OptUUID	First UUID (in UUIDs NBT)?		Absent
16	OptUUID	Second UUID (in UUIDs NBT)?		Absent

Mooshroom

Extends Cow.

No additional metadata.

Index	Type	Meaning		Default
15	String	Variant ("red" or "brown")		red

Pillager

Extends Abstract Illlager.

Index	Type	Meaning		Default
13	Boolean	Using crossbow		false

Ocelot

Extends TameableAnimal Ageable.

Index	Type	Meaning		Default
15	VarInt	Type (0 = untamed, 1 = tuxedo, 2 = tabby, 3 = siamese). Used to render regardless as to whether it is tamed or not.		0
13	Boolean	Is trusting		false

Status	Description
40	Spawn smoke particles (trust gaining failed)
41	Spawn heart particles (trust gaining succeeded)

Cat

Extends TameableAnimal.

Index	Type	Meaning		Default
15	VarInt	Type (0 = tabby, 1 = black, 2 = red, 3 = siamese, 4 = british_shorthair, 5 = calico, 6 = persian, 7 = ragdoll, 8 = white, 9 = all_black)		1
16	Boolean	Unknown		false
17	Boolean	Unknown		false
18	VarInt	Collar color (values are those used with dyes)		14 (Red)

Horse

Extends AbstractHorse.

	The following information needs to be added to this page:
	What was Armor replaced with? Something in the Entity Equipment packet, maybe?

Index	Type	Meaning		Default
15	VarInt	Variant (Color & Style)		0
16	VarInt	Armor (0: none, 1: iron, 2: gold, 3: diamond)		0 (none)
17	Slot	Armor Item (Forge only)		Empty

Trader Llama

Extends Llama.

No additional metadata.

Villager

Extends Ageable.

Index	Type	Meaning		Default
13	VarInt Villager Data	Villager Data		0 Plains/None/1

Zombie Villager

Extends Zombie.

Index	Type	Meaning		Default
16	Boolean	Is converting		false
17	VarInt Villager Data	Profession Villager Data		0 Plains/None/1

Block Actions

No changes so far.

Plugin Channels

minecraft:book_open

Server to client

When a player right clicks with a signed book. This tells the client to open the book GUI.

The payload is a VarInt enum for the selected hand: 0 for the main hand, 1 for the offhand.

Replaced with Open Book packet.

minecraft:trader_list

Server to client

The list of trades a villager NPC is offering.

Replaced with Trade List packet.

Play

Clientbound

Spawn Object

Sent by the server when a vehicle or other object is created.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Play	Client	Entity ID	VarInt	EID of the object
			Object UUID	UUID
			Type	Byte VarInt	The type of object. (see Entities#Objects) Uses the same entity type IDs as in Spawn Mob
			X	Double
			Y	Double
			Z	Double
			Pitch	Angle
			Yaw	Angle
			Data	Int	Meaning dependent on the value of the Type field, see Object Data for details.
			Velocity X	Short	Same units as Entity Velocity. Always sent, but only used when Data is greater than 0 (except for some entities which always ignore it; see Object Data for details).
			Velocity Y	Short
			Velocity Z	Short

Update Block Entity

Sets the block entity associated with the block at the given location.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x09	Play	Client	Location	Position
			Action	Unsigned Byte	The type of update to perform, see below
			NBT Data	NBT Tag	Data to set. May be a TAG_END (0), in which case the block entity at the given location is removed (though this is not required since the client will remove the block entity automatically on chunk unload or block removal)

Action field:

• 1: Set data of a mob spawner (everything except for SpawnPotentials: current delay, min/max delay, mob to be spawned, spawn count, spawn range, etc.)
• 2: Set command block text (command and last execution status)
• 3: Set the level, primary, and secondary powers of a beacon
• 4: Set rotation and skin of mob head
• 5: Declare a conduit
• 6: Set base color and patterns on a banner
• 7: Set the data for a Structure tile entity
• 8: Set the destination for a end gateway
• 9: Set the text on a sign
• 10: Declare a shulker box, no data appears to be sent and the client seems to do fine without this packet. Perhaps it is a leftover from earlier versions?
• 11: Declare a bed
• 12: Set data of a jigsaw block
• 13: Set items in a campfire

Open Horse Window

This packet is used exclusively for opening the horse GUI. Open Window is used for all other GUIs, and now has ID 0x59.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14	Play	Client	Window ID?	Byte
			Number of slots?	VarInt
			Entity ID?	Integer

Chunk Data

Main article: Chunk Format

See also: #Unload Chunk

The server only sends skylight information for chunk pillars in the Overworld, it's up to the client to know in which dimenison the player is currently located. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent. This packet also sends all block entities in the chunk (though sending them is not required; it is still legal to send them with Update Block Entity later).

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Heightmaps	NBT	Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries at 9 bits per entry).
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.

Data structure

The data section of the packet contains most of the useful data for the chunk.

Field Name	Field Type	Notes
Data	Array of Chunk Section	The number of elements in the array is equal to the number of bits set in Primary Bit Mask. Sections are sent bottom-to-top, i.e. the first section, if sent, extends from Y=0 to Y=15.
Biomes	Optional Int Array	Only sent if Ground-Up Continuous is true; 256 entries if present

Chunk Section structure

A Chunk Section is defined in terms of other data types. A Chunk Section consists of the following fields:

Field Name	Field Type	Notes
Block count	Short	Number of non-air blocks present in the chunk section, for lighting purposes. "Non-air" is defined as any block other than air, cave air, and void air (in particular, note that fluids such as water are still counted).
Bits Per Block	Unsigned Byte	Determines how many bits are used to encode a block. Note that not all numbers are valid here.
Palette	Varies	See below for the format.
Data Array Length	VarInt	Number of longs in the following array
Data Array	Array of Long	Compacted list of 4096 indices pointing to state IDs in the Palette
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 is given for each block with increasing x coordinates, within rows of increasing z coordinates, within layers of increasing y coordinates. For the half-byte light arrays, even-indexed items (those with an even x coordinate, starting at 0) are packed into the low bits, odd-indexed into the high bits.

Map Data

Updates a rectangular area on a map item.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x26	Play	Client	Map ID		VarInt		Map ID of the map being modified
			Scale		Byte		From 0 for a fully zoomed-in map (1 block per pixel) to 4 for a fully zoomed-out map (16 blocks per pixel)
			Tracking Position		Boolean		Specifies whether player and item frame icons are shown
			Locked		Boolean		True if the map has been locked in a cartography table
			Icon Count		VarInt		Number of elements in the following array
			Icon	Type	Array	VarInt enum	See below
				X		Byte	Map coordinates: -128 for furthest left, +127 for furthest right
				Z		Byte	Map coordinates: -128 for highest, +127 for lowest
				Direction		Byte	0-15
				Has Display Name		Boolean
			Display Name	Optional Chat		Only present if previous Boolean is true
			Columns		Byte		Number of columns updated
			Rows		Optional Byte		Only if Columns is more than 0; number of rows updated
			X		Optional Byte		Only if Columns is more than 0; x offset of the westernmost column
			Z		Optional Byte		Only if Columns is more than 0; z offset of the northernmost row
			Length		Optional VarInt		Only if Columns is more than 0; length of the following array
			Data		Optional Array of Unsigned Byte		Only if Columns is more than 0; see Map item format

For icons, a direction of 0 is a vertical icon and increments by 22.5° (360/16).

Types are based off of rows and columns in map_icons.png:

Icon type	Result
0	White arrow (players)
1	Green arrow (item frames)
2	Red arrow
3	Blue arrow
4	White cross
5	Red pointer
6	White circle (off-map players)
7	Small white circle (far-off-map players)
8	Mansion
9	Temple
10	White Banner
11	Orange Banner
12	Magenta Banner
13	Light Blue Banner
14	Yellow Banner
15	Lime Banner
16	Pink Banner
17	Gray Banner
18	Light Gray Banner
19	Cyan Banner
20	Purple Banner
21	Blue Banner
22	Brown Banner
23	Green Banner
24	Red Banner
25	Black Banner
26	Treasure marker

Open Book

Sent when a player right clicks with a signed book. This tells the client to open the book GUI.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x2C	Play	Client	Hand	VarInt enum	0: Main hand, 1: Off hand

Use Bed

This packet tells that a player goes to bed.

The client with the matching Entity ID will go into bed mode.

This Packet is sent to all nearby players including the one sent to bed.

Any packets sent with a location not currently occupied by a bed will be ignored by clients.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x33	Play	Client	Entity ID	VarInt	Sleeping player's EID
			Location	Position	Block location of the head part of the bed

Entity Sound Effect

Plays a sound effect from an entity.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x4F	Play	Client	Sound ID	VarInt	ID of hardcoded sound event (events as of 18w48a)
			Sound Category	VarInt Enum	The category that this sound will be played from (current categories)
			Entity ID	VarInt
			Volume	Float	1.0 is 100%, capped between 0.0 and 1.0 by Notchian clients
			Pitch	Float	Float between 0.5 and 2.0 by Notchian clients

Declare Recipes

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x54 0x55	Play	Client	Num Recipes		VarInt		Number of elements in the following array
			Recipe	Recipe ID	Array	Identifier
				Type		String Identifier	The recipe serializer, see below
				Recipe ID		Identifier
				Data		Optional, varies	Additional data for the recipe. For some types, there will be no data.

Recipe serializers:

Serializer	Description	Data
minecraft:crafting_shapeless	Shapeless crafting recipe. All items in the ingredient list must be present, but in any order/slot.	As follows: Name Type Description Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Ingredient count VarInt Number of elements in the following array Ingredients Array of Ingredient Result Slot
minecraft:crafting_shaped	Shaped crafting recipe. All items must be present in the same pattern (which may be flipped horizontally or translated)	As follows: Name Type Description Width VarInt Height VarInt Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Ingredients Array of Ingredient Length is width * height. Indexed by x + (y * width). Result Slot
minecraft:crafting_special_armordye	Recipe for dying leather armor	None
minecraft:crafting_special_bookcloning	Recipe for copying contents of written books	None
minecraft:crafting_special_mapcloning	Recipe for copying maps	None
minecraft:crafting_special_mapextending	Recipe for adding paper to maps	None
minecraft:crafting_special_firework_rocket	Recipe for making firework rockets	None
minecraft:crafting_special_firework_star	Recipe for making firework stars	None
minecraft:crafting_special_firework_star_fade	Recipe for making firework stars fade between multiple colors	None
minecraft:crafting_special_repairitem	Recipe for repairing items via crafting	None
minecraft:crafting_special_tippedarrow	Recipe for crafting tipped arrows	None
minecraft:crafting_special_bannerduplicate	Recipe for copying banner patterns	None
minecraft:crafting_special_banneraddpattern	Recipe for adding patterns to banners	None
minecraft:crafting_special_shielddecoration	Recipe for applying a banner's pattern to a shield	None
minecraft:crafting_special_shulkerboxcoloring	Recipe for recoloring a shulker box	None
minecraft:crafting_special_suspiciousstew	Recipe for crafting suspicious stew with various affects.	None
minecraft:smelting	Smelting recipe	All of these have the same format, as follows: Name Type Description Group String Used to group similar recipes together in the recipe book. Ingredient Ingredient Result Slot Experience Float Cooking time VarInt
minecraft:blasting	Recipes in a blast furnace.
minecraft:smoking	Recipes in a smoker.
minecraft:campfire_cooking	Recipes in a campfire.

Ingredient is defined as:

Name	Type	Description
Count	VarInt	Number of elements in the following array
Items	Array of Slot	Any item in this array may be used for the recipe. The count of each item should be 1.

Tags

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x55 0x56	Play	Client	Block Tags	(See below)	IDs are block IDs
			Item Tags	(See below)	IDs are item IDs
			Fluid Tags	(See below)	IDs are fluid IDs
			Entity Tags	(See below)	IDs are entity type IDs

Update Light

Updates light levels for a chunk.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x57	Play	Client	Chunk X	VarInt	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	VarInt	Chunk coordinate (block coordinate divided by 16, rounded down)
			Sky Light Mask	VarInt	Mask containing 18 bits, with the lowest bit corresponding to chunk section -1 (in the void, y=-16 to y=-1) and the highest bit for chunk section 16 (above the world, y=256 to y=271)
			Block Light Mask	VarInt	Mask containing 18 bits, with the same order as sky light
			Empty Sky Light Mask	VarInt	Mask containing 18 bits, which indicates sections that have 0 for all their sky light values. If a section is set in both this mask and the main sky light mask, it is ignored for this mask and it is included in the sky light arrays (the notchian server does not create such masks). If it is only set in this mask, it is not included in the sky light arrays.
			Empty Block Light Mask	VarInt	Mask containing 18 bits, which indicates sections that have 0 for all their block light values. If a section is set in both this mask and the main block light mask, it is ignored for this mask and it is included in the block light arrays (the notchian server does not create such masks). If it is only set in this mask, it is not included in the block light arrays.
			Sky Light arrays	Array of arrays of 2048 bytes	There is 1 array for each bit set to true in the sky light mask, starting with the lowest value. Half a byte per light value.
			Block Light arrays	Array of arrays of 2048 bytes	There is 1 array for each bit set to true in the block light mask, starting with the lowest value. Half a byte per light value.

Individual block or sky light arrays are is given for each block with increasing x coordinates, within rows of increasing z coordinates, within layers of increasing y coordinates. Even-indexed items (those with an even x coordinate, starting at 0) are packed into the low bits, odd-indexed into the high bits.

Open Window

This is sent to the client when it should open an inventory, such as a chest, workbench, or furnace. This message is not sent anywhere for clients opening their own inventory. For horses, use Open Horse Window

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14 0x58	Play	Client	Window ID	Unsigned Byte VarInt	A unique id number for the window to be displayed. Notchian server implementation is a counter, starting at 1.
			Window Type	String (32) VarInt	The window type to use for display. See Inventory for a list contained in the minecraft:menu regisry.
			Window Title	Chat	The title of the window
			Number Of Slots	Unsigned Byte	Number of slots in the window (excluding the number of slots in the player inventory). Always 0 for non-storage windows (e.g. Workbench, Anvil).
			Entity ID	Optional Int	EntityHorse's EID. Only sent when Window Type is “EntityHorse”

Trade List

The list of trades a villager NPC is offering.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x59	Play	Client
			Window ID		VarInt		The ID of the window that is open; this is an int rather than a byte.
			Size		Byte		The number of trades in the following array
			Trades	Input item 1	Array	Slot	The first item the villager is buying
				Output item		Slot	The item the villager is selling
				Has second item		Boolean	Whether there is a second item
				Input item 2		Optional Slot	The second item the villager is buying; only present if they have a second item.
				Trade disabled		Boolean	True if the trade is disabled; false if the trade is enabled.
				Number of trade uses		Integer	Number of times the trade has been used so far
				Maximum number of trade uses		Integer	Number of times this trade can be used

Serverbound

Recipe Book Data

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x1B	Play	Server	Type		VarInt	Determines the format of the rest of the packet
			Type	Field Name
			0: Displayed Recipe	Recipe ID	Identifier	A recipe ID
			1: Recipe Book States	Crafting Recipe Book Open	Boolean	Whether the player has the crafting recipe book currently opened/active.
				Crafting Recipe Filter Active	Boolean	Whether the player has the crafting recipe book filter option currently active.
				Smelting Recipe Book Open	Boolean	Whether the player has the smelting recipe book currently opened/active.
				Smelting Recipe Filter Active	Boolean	Whether the player has the smelting recipe book filter option currently active.
				Blasting Recipe Book Open	Boolean	May be swapped with smoking recipe book. Also, the notchian client appears to use the same value for both of those books currently.
				Blasting Recipe Filter Active	Boolean	May be swapped with smoking recipe book. Also, the notchian client appears to use the same value for both of those books currently.
				Smoking Recipe Book Open	Boolean
				Smoking Recipe Filter Active	Boolean

The Recipe Book Status type is sent when one of the states changes.

Player Block Placement

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x29	Play	Server	Location	Position	Block position
			Face	VarInt Enum	The face on which the block is placed (as documented at Player Digging)
			Hand	VarInt Enum	The hand from which the block is placed; 0: main hand, 1: off hand
			Location	Position	Block position
			Face	VarInt Enum	The face on which the block is placed (as documented at Player Digging)
			Cursor Position X	Float	The position of the crosshair on the block, from 0 to 1 increasing from west to east
			Cursor Position Y	Float	The position of the crosshair on the block, from 0 to 1 increasing from bottom to top
			Cursor Position Z	Float	The position of the crosshair on the block, from 0 to 1 increasing from north to south
			Inside block	Boolean	True when the player's head is inside of a block.

Upon placing a block, this packet is sent once.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to sixteen pixel in the default resource pack. For example, let's say a slab is being placed against the south face of a full block. The Cursor Position X will be higher if the player was pointing near the right (east) edge of the face, lower if pointing near the left. The Cursor Position Y will be used to determine whether it will appear as a bottom slab (values 0.0–0.5) or as a top slab (values 0.5-1.0). The Cursor Position Z should be 1.0 since the player was looking at the southernmost part of the block.

Inside block is true when a player's head (specifically eyes) are inside of a block's collision. In 1.13 and later versions, collision is rather complicated and individual blocks can have multiple collision boxes. For instance, a ring of vines has a non-colliding hole in the middle. This value is only true when the player is directly in the box. In practice, though, this value is only used by scaffolding to place in front of the player when sneaking inside of it (other blocks will place behind when you intersect with them -- try with glass for instance).

Handshaking

Clientbound

There are no clientbound packets in the Handshaking state, since the protocol immediately switches to a different state after the client sends the first packet.

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Handshaking	Server	Protocol Version	VarInt	See protocol version numbers (currently 404 461)
			Server Address	String	Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information.
			Server Port	Unsigned Short	Default is 25565. The Notchian server does not use this information.
			Next State	VarInt Enum	1 for status, 2 for login

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.