Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.8.9, protocol 47) to the current pre-release (currently 16w04a, protocol 97). 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

• Chunk Section
• Entity Metadata

Packets

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre
Play clientbound
0x0E 0x00	Spawn Object	Current	Pre
0x11 0x01	Spawn Experience Orb	Current	(unchanged)
0x2C 0x02	Spawn Global Entity	Current	(unchanged)
0x0F 0x03	Spawn Mob	Current	Pre
0x10 0x04	Spawn Painting	Current	(unchanged)
0x0C 0x05	Spawn Player	Current	Pre
0x0B 0x06	Animation	Current	(unchanged)
0x37 0x07	Statistics	Current	(unchanged)
0x25 0x08	Block Break Animation	Current	(unchanged)
0x35 0x09	Update Block Entity	Current	(unchanged)
0x24 0x0A	Block Action	Current	(unchanged)
0x23 0x0B	Block Change	Current	(unchanged)
0x0C	Boss Bar		Pre
0x41 0x0D	Server Difficulty	Current	(unchanged)
0x3A 0x0E	Tab-Complete	Current	(unchanged)
0x02 0x0F	Chat Message	Current	(unchanged)
0x22 0x10	Multi Block Change	Current	(unchanged)
0x32 0x11	Confirm Transaction	Current	(unchanged)
0x2E 0x12	Close Window	Current	(unchanged)
0x2D 0x13	Open Window	Current	(unchanged)
0x30 0x14	Window Items	Current	(unchanged)
0x31 0x15	Window Property	Current	(unchanged)
0x2F 0x16	Set Slot	Current	(unchanged)
0x17	Set Cooldown		Pre
0x3F 0x18	Plugin Message	Current	(unchanged)
0x2F 0x19	Named Sound Effect	Current	Pre
0x40 0x1A	Disconnect	Current	(unchanged)
0x1A 0x1B	Entity Status	Current	Pre
0x27 0x1C	Explosion	Current	(unchanged)
0x1D	Unload Chunk		Pre
0x2B 0x1E	Change Game State	Current	(unchanged)
0x00 0x1F	Keep Alive	Current	(unchanged)
0x21 0x20	Chunk Data	Current	Pre
0x28 0x21	Effect	Current	(unchanged)
0x2A 0x22	Particle	Current	(unchanged)
0x01 0x23	Join Game	Current	(unchanged)
0x34 0x24	Map	Current	Pre
0x15 0x25	Entity Relative Move	Current	(unchanged)
0x17 0x26	Entity Look And Relative Move	Current	(unchanged)
0x16 0x27	Entity Look	Current	(unchanged)
0x14 0x28	Entity	Current	(unchanged)
0x29	Vehicle Move		Pre
0x36 0x2A	Open Sign Editor	Current	(unchanged)
0x39 0x2B	Player Abilities	Current	(unchanged)
0x42 0x2C	Combat Event	Current	Pre
0x38 0x2D	Player List Item	Current	(unchanged)
0x08 0x2E	Player Position And Look	Current	Pre
0x0A 0x2F	Use Bed	Current	(unchanged)
0x13 0x30	Destroy Entities	Current	(unchanged)
0x1E 0x31	Remove Entity Effect	Current	(unchanged)
0x48 0x32	Resource Pack Send	Current	(unchanged)
0x07 0x33	Respawn	Current	(unchanged)
0x19 0x34	Entity Head Look	Current	(unchanged)
0x44 0x35	World Border	Current	(unchanged)
0x43 0x36	Camera	Current	(unchanged)
0x09 0x37	Held Item Change	Current	(unchanged)
0x3D 0x38	Display Scoreboard	Current	(unchanged)
0x1C 0x39	Entity Metadata	Current	(unchanged)
0x1B 0x3A	Attach Entity	Current	(unchanged)
0x12 0x3B	Entity Velocity	Current	(unchanged)
0x04 0x3C	Entity Equipment	Current	Pre
0x1F 0x3D	Set Experience	Current	(unchanged)
0x06 0x3E	Update Health	Current	(unchanged)
0x3B 0x3F	Scoreboard Objective	Current	(unchanged)
0x40	Set Passengers		Pre
0x3E 0x41	Teams	Current	Pre
0x3C 0x42	Update Score	Current	(unchanged)
0x05 0x43	Spawn Position	Current	(unchanged)
0x03 0x44	Time Update	Current	(unchanged)
0x45 0x45	Title	Current	(unchanged)
0x33 0x46	Update Sign	Current	(unchanged)
0x47	Sound Effect		Pre
0x47 0x48	Player List Header And Footer	Current	(unchanged)
0x0D 0x49	Collect Item	Current	(unchanged)
0x18 0x4A	Entity Teleport	Current	(unchanged)
0x20 0x4B	Entity Properties	Current	Pre
0x1D 0x4C	Entity Effect	Current	(unchanged)
0x26	Map Chunk Bulk	Current
0x46	Set Compression	Current
0x49	Update Entity NBT	Current
Play serverbound
0x00	Teleport Confirm		Pre
0x14 0x01	Tab-Complete	Current	Pre
0x01 0x02	Chat Message	Current	(unchanged)
0x16 0x03	Client Status	Current	Pre
0x15 0x04	Client Settings	Current	Pre
0x0F 0x05	Confirm Transaction	Current	(unchanged)
0x11 0x06	Enchant Item	Current	(unchanged)
0x0E 0x07	Click Window	Current	(unchanged)
0x0D 0x08	Close Window	Current	(unchanged)
0x17 0x09	Plugin Message	Current	(unchanged)
0x02 0x0A	Use Entity	Current	Pre
0x00 0x0B	Keep Alive	Current	(unchanged)
0x04 0x0C	Player Position	Current	(unchanged)
0x06 0x0D	Player Position And Look	Current	(unchanged)
0x05 0x0E	Player Look	Current	(unchanged)
0x03 0x0F	Player	Current	(unchanged)
0x10	Vehicle Move (serverbound)		Pre
0x11	Steer Boat		Pre
0x13 0x12	Player Abilities	Current	(unchanged)
0x07 0x13	Player Digging	Current	Pre
0x0B 0x14	Entity Action	Current	Pre
0x0C 0x15	Steer Vehicle	Current	(unchanged)
0x19 0x16	Resource Pack Status	Current	(unchanged)
0x09 0x17	Held Item Change	Current	(unchanged)
0x10 0x18	Creative Inventory Action	Current	(unchanged)
0x12 0x19	Update Sign	Current	Pre
0x0A 0x1A	Animation	Current	Pre
0x18 0x1B	Spectate	Current	(unchanged)
0x08 0x1C	Player Block Placement	Current	Pre
0x1D	Use Item		Pre
Status clientbound
0x00	Response	Current	(unchanged)
0x01	Pong	Current	(unchanged)
Status serverbound
0x00	Request	Current	(unchanged)
0x01	Ping	Current	(unchanged)
Login clientbound
0x00	Disconnect	Current	(unchanged)
0x01	Encryption Request	Current	(unchanged)
0x02	Login Success	Current	(unchanged)
0x03	Set Compression	Current	(unchanged)
Login serverbound
0x00	Login Start	Current	(unchanged)
0x01	Encryption Response	Current	(unchanged)

New/modified data types

Chunk Section

Format is now:

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 block ID for the first 9 bits, and the block damage value for the last 4 bits. For example, diorite (block ID 1 for minecraft:stone with damage 3) would be encoded as 000000001 0011.

Entity Metadata

Format is now 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 Byte 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	Slot
6	Boolean
7	Vector3F (Array of Float)	3 elements
8	Position
9	OptPosition (Boolean + Optional Position)	Position is present if the Boolean is set to true
10	Direction (VarInt)	???
11	OptUUID (Boolean + Optional UUID)	UUID is present if the Boolean is set to true
12	BlockID (VarInt)	id << 4 | data

Entity class	Index	Type	Meaning
Entity	0	Byte	Status bit mask, added 0x40 - glowing effect.
	1	VarInt	Air
	2	String	Custom Name
	3	Boolean	Is Custom Name Visible
	4	Boolean	Is Silent
AreaEffectCloud extends Entity	5	Float	Radius
	6	VarInt	Color (only for mob spell particle)
	7	Boolean	Unknown (seems that true value ignore radius and show effect as single point, not area)
	8	VarInt	Particle ID
Arrow extends Entity	5	Byte	Is Critical
TippedArrow extends Arrow	6	VarInt	Color
Boat extends Entity	5	VarInt	Time Since Last Hit
	6	VarInt	Forward Direction
	7	Float	Damage Taken
	8	VarInt	Type
EnderCrystal extends Entity	5	OptPosition	Beam Target
	6	Boolean	Show Bottom
Fireball extends Entity	no additional metadata
WitherSkull extends Fireball	5	Boolean	Invulnerable
Fireworks extends Entity	5	Slot	Firework Info
Hanging extends Entity	no additional metadata
ItemFrame extends Hanging	5	Slot	Item
	6	VarInt	Rotation
Item extends Entity	5	Slot	Item
Living extends Entity	5	Byte	Unknown (probably indicates which hand is currently used)
	6	Float	Health
	7	VarInt	Potion Effect Color
	8	Boolean	Is Potion Effect Ambient
	9	VarInt	Number of Arrows in Entity
ArmorStand extends Living
	10	Byte	Status bit mask
	11	Vector3F	Head rotation
	12	Vector3F	Body rotation
	13	Vector3F	Left arm rotation
	14	Vector3F	Right arm rotation
	15	Vector3F	Left leg rotation
	16	Vector3F	Right leg rotation
Insentient extends Living	10	Byte	Status bit mask (NoAI, Left handed)
Ambient extends Insentient	no additional metadata
Bat extends Ambient	11	Byte	Is Hanging
Creature extends Insentient	no additional metadata
Ageable extends Creature	11	Boolean	Is Baby
Animal extends Ageable	no additional metadata
Horse extends Animal	12	Byte	Status bit mask
	13	VarInt	Type
	14	VarInt	Variant
	15	OptUUID	Owner's UUID
	16	VarInt	Armor
Pig extends Animal	12	Boolean	Has Saddle
Rabbit extends Animal	12	VarInt	Type
Sheep extends Animal	12	Byte	Status bit mask
TameableAnimal extends Animal	12	Byte	Status bit mask (sitting, tamed)
	13	OptUUID	Owner's UUID
Ocelot extends TameableAnimal	14	VarInt	Type
Wolf extends TameableAnimal	14	Float	Damage Taken (used for tail rotation)
	15	Boolean	Is Begging
	16	VarInt	Collar Color
Villager extends Ageable	12	VarInt	Unknown
Golem extends Creature	no additional metadata
IronGolem extends Golem	11	Byte	Is Player Created
Shulker extends Golem	11	Direction	Facing Direction
	12	OptPosition	Attachment Position
	13	Byte	Shield Height
Monster extends Creature	no additional metadata
Blaze extends Monster	11	Byte	Is On Fire
Creeper extends Monster	11	VarInt	State (-1 = Idle, 1 = Fuse)
	12	Boolean	Is Powered
	13	Boolean	Is Ignited
Guardian extends Monster	11	Byte	Status bit mask (elderly, retracting spikes)
	12	VarInt	Target EID
Skeleton extends Monster	11	VarInt	Type
	12	Boolean	Unknown (something hand related)
Spider extends Monster	11	Byte	Is Climbing
Witch extends Monster	11	Boolean	Is Aggresive
Wither extends Monster	11	VarInt	First Head's Target
	12	VarInt	Second Head's Target
	13	VarInt	Third Head's Target
	14	VarInt	Invulnerable Time
Zombie extends Monster	11	Boolean	Is Baby
	12	VarInt	Is Villager (profession)
	13	Boolean	Is Converting
	14	Boolean	Are Hands Rised Up
Enderman extends Monster	11	Block ID	Carried Block
	12	Boolean	Is Screaming
EnderDragon extends Insentient	11	VarInt	Dragon Phase
Flying extends Insentient	no additional metadata
Ghast extends Flying	11	Boolean	Is Attacking
Slime extends Insentient	11	VarInt	Size
Minecart extends Entity	5	VarInt	Shaking Power
	6	VarInt	Shaking Direction
	7	Float	Shaking Multiplier
	8	VarInt	Block ID and Meta
	9	VarInt	Block Y Position
	10	Boolean	Show Block
MinecartCommandBlock extends Minecart	11	String	Command
	12	Chat	Last Output
MinecartFurnace extends Minecart	11	Boolean	Is Powered
TNTPrimed extends Entity	5	VarInt	Fuse Time

Entity classes also recursively use fields from classes they extend.

Handshaking

Clientbound

No changes so far.

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 47 95)
			Server Address	String	hostname or IP, e.g. localhost or 127.0.0.1 (does this support IPv6?)
			Server Port	Unsigned Short	default is 25565
			Next State	VarInt Enum	1 for status, 2 for login

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
0x0E 0x00	Play	Client	Entity ID	VarInt	EID of the object
			Object UUID	UUID
			Type	Byte	The type of object (see Entities#Objects)
			X	Int Double	X position as a Absolute position
			Y	Int Double	Y position as a Absolute position
			Z	Int Double	Z position as a Absolute position
			Pitch	Angle
			Yaw	Angle
			Data	Int	Meaning dependent on the value of the Type field, see Object Data for details.
			Velocity X	Optional Short Short	Only sent if the Data field is nonzero. Same units as Entity Velocity.
			Velocity Y	Optional Short Short	Only sent if the Data field is nonzero. Same units as Entity Velocity.
			Velocity Z	Optional Short Short	Only sent if the Data field is nonzero. Same units as Entity Velocity.

Spawn Mob

Sent by the server when a mob entity is spawned.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0F 0x03	Play	Client	Entity ID	VarInt
			Entity UUID	UUID
			Type	Unsigned Byte	The type of mob. See Entities#Mobs
			X	Int Double	X position as a Absolute position
			Y	Int Double	Y position as a Absolute position
			Z	Int Double	Z position as a Absolute position
			Yaw	Angle
			Pitch	Angle
			Head Pitch	Angle
			Velocity X	Short	Same units as Entity Velocity
			Velocity Y	Short	Same units as Entity Velocity
			Velocity Z	Short	Same units as Entity Velocity
			Metadata	Entity Metadata

Spawn Player

This packet is sent by the server when a player comes into visible range, not when a player joins.

This packet must be sent after the Player List Item (Play, 0x38, clientbound) packet that adds the player data for the client to use when spawning a player. If the Player List Item for the player spawned by this packet is not present when this packet arrives, Notchian clients will not spawn the player entity. The Player List Item packet includes skin/cape data.

Servers can, however, safely spawn player entities for players not in visible range. The client appears to handle it correctly.

When in online-mode the UUIDs must be valid and have valid skin blobs, in offline-mode UUID v3 is used.

For NPCs UUID v2 should be used. Note:

<+Grum> i will never confirm this as a feature you know that :)

In an example UUID, xxxxxxxx-xxxx-Yxxx-xxxx-xxxxxxxxxxxx, the UUID version is specified by Y. So, for UUID v3, Y will always be 3, and for UUID v2, Y will always be 2.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0C 0x05	Play	Client	Entity ID	VarInt	Player's EID
			Player UUID	UUID
			X	Int Double	X position as a Absolute position
			Y	Int Double	Y position as a Absolute position
			Z	Int Double	Z position as a Absolute position
			Yaw	Angle
			Pitch	Angle
			Current Item	Short	The item the player is currently holding. Note that this should be 0 for “no item”, unlike -1 used in other packets.
			Metadata	Entity Metadata

Boss Bar

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x49 0x0C	Play	Client	UUID		UUID	Unique ID for this bar
			Action		VarInt Enum	Determines the layout of the remaining packet
			Action	Field Name
			0: add	Title	Chat
				Health	Float	From 0 to 1. Values greater than 1 do not crash the client, and start rendering part of a second health bar at around 1.5.
				Color	VarInt Enum	Color ID (see below)
				Division	VarInt Enum	Type of division (see below)
				Flags	Unsigned Byte	Bit mask: 0x1 should darken sky, 0x2: is dragon bar (used to play end music)
			1: remove	no fields	no fields	Removes this boss bar
			2: update health	Health	Float	as above
			3: update title	Title	Chat
			4: update style	Color	VarInt Enum	Color ID (see below)
				Dividers	VarInt Enum	as above
			5: update flags	Flags	Unsigned Byte	as above

ID	Color
0	Pink
1	Blue
2	Red
3	Green
4	Yellow
5	Purple
6	White

ID	Type of division
0	No division
1	6 notches
2	10 notches
3	12 notches
4	20 notches

Set Cooldown

Applies a cooldown period to an item type.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x17	Play	Client	Item ID	VarInt	ID of the item to apply a cooldown to.
			Cooldown Ticks	VarInt	Number of ticks to apply a cooldown for.

Named Sound Effect

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x2F 0x19	Play	Client	Sound Name	String	All known sound effect names can be seen here
			Sound Category	VarInt Enum	The category that this sound will be played from (current categories)
			Effect Position X	Int	Effect X multiplied by 8
			Effect Position Y	Int	Effect Y multiplied by 8
			Effect Position Z	Int	Effect Z multiplied by 8
			Volume	Float	1 is 100%, can be more
			Pitch	Unsigned Byte	63 is 100%, can be more

Entity Status

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1A 0x1B	Play	Client	Entity ID	Int
			Entity Status	Byte Enum	See below

Entity Status	Meaning
1	Sent when resetting a mob spawn minecart's timer — appears to be unused by the client
2	Living Entity hurt
3	Living Entity dead
4	Iron Golem throwing up arms
6	Wolf/Ocelot/Horse taming — Spawn “heart” particles
7	Wolf/Ocelot/Horse tamed — Spawn “smoke” particles
8	Wolf shaking water — Trigger the shaking animation
9	(of self) Eating accepted by server
10	Sheep eating grass
10	Play TNT ignite sound
11	Iron Golem handing over a rose
12	Villager mating — Spawn “heart” particles
13	Spawn particles indicating that a villager is angry and seeking revenge
14	Spawn happy particles near a villager
15	Witch animation — Spawn “magic” particles
16	Play zombie converting into a villager sound
17	Firework exploding
18	Animal in love (ready to mate) — Spawn “heart” particles
19	Reset squid rotation
20	Spawn explosion particle — works for some living entities
21	Play guardian sound — works for every entity
22	Enables reduced debug for players
23	Disables reduced debug for players
24–28	Sets op permission level 0–4 for players

Unload Chunk

Tells the client to unload a chunk.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1D	Play	Client	Chunk X	Int	Chunk X coordinate
			Chunk Z	Int	Chunk Z coordinate

Chunk Data

Chunk pillars are not unloaded by the client automatically. To unload chunk pillars, send this packet with Ground-Up Continuous=true and no 16^3 chunks (eg. Primary Bit Mask=0) send an Unload Chunk packet with the chunk's X and Z coordinates. 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.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x21 0x20	Play	Client	Chunk X	Int	Chunk X coordinate
			Chunk Z	Int	Chunk Z coordinate
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	Unsigned Short VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data follows in the compressed data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.

Map

Updates a rectangular area on a map item.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x34 0x24	Play	Client	Item Damage		VarInt		The damage value (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 the icons are shown
			Icon Count		VarInt		Number of elements in the following array
			Icon	Direction And Type	Array	Byte	0xF0 = Direction, 0x0F = Type
				X		Byte
				Z		Byte
			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 Byte Enum		Only if Columns is more than 0; see Map item format

Vehicle Move

Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x29	Play	Client	X	Double	Absolute position (X coordinate)
			Y	Double	Absolute position (Y coordinate)
			Z	Double	Absolute position (Z coordinate)
			Yaw	Float	Absolute rotation on the vertical Axis, in degrees
			Pitch	Float	Absolute rotation on the horizontal Axis, in degrees

Combat Event

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x42 0x2C	Play	Client	Event		VarInt Enum	Determines the layout of the remaining packet
			Event	Field Name
			0: enter combat	no fields	no fields
			1: end combat	Duration	VarInt
				Entity ID	Int
			2: entity dead	Player ID	VarInt
				Entity ID	Int
				Message	String Chat

Player Position And Look

Updates the player's position on the server.

If the distance between the last known position of the player on the server and the new position set by this packet is greater than 100 meters, the client will be kicked for “You moved too quickly :( (Hacking?)”.

Also if the fixed-point number of X or Z is set greater than 3.2E7D the client will be kicked for “Illegal position”.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0, -1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw in degrees of a player standing at point (x0, z0) and looking towards point (x, z) can be calculated with:

l = x-x0
w = z-z0
c = sqrt( l*l + w*w )
alpha1 = -arcsin(l/c)/PI*180
alpha2 =  arccos(w/c)/PI*180
if alpha2 > 90 then
    yaw = 180 - alpha1
else
    yaw = alpha1

You can get a unit vector from a given yaw/pitch via:

x = -cos(pitch) * sin(yaw)
y = -sin(pitch)
z =  cos(pitch) * cos(yaw)

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x08 0x2E	Play	Client	X	Double	Absolute or relative position, depending on Flags
			Y	Double	Absolute or relative position, depending on Flags
			Z	Double	Absolute or relative position, depending on Flags
			Yaw	Float	Absolute or relative rotation on the X Axis, in degrees
			Pitch	Float	Absolute or relative rotation on the Y Axis, in degrees
			Flags	Byte	Bit field, see below
			Teleport ID	VarInt	Client should confirm this packet with Teleport Confirm containing the same Teleport ID

About the Flags field:

<Dinnerbone> It's a bitfield, X/Y/Z/Y_ROT/X_ROT. If X is set, the x value is relative and not absolute.

Field	Bit
X	0x01
Y	0x02
Z	0x04
Y_ROT	0x08
X_ROT	0x10

Entity Equipment

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x04 0x3C	Play	Client	Entity ID	VarInt	Entity's EID
			Slot	Short VarInt Enum	Equipment slot. 0: main hand, 1: off hand, 1–4 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet)
			Item	Slot

Set Passengers

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x40	Play	Client	Entity ID	VarInt	Vehicle's EID
			Passengers	Array of VarInt	EIDs of entity's passengers

Teams

Creates and updates teams.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x3E 0x41	Play	Client	Team Name	String	A unique name for the team. (Shared with scoreboard).
			Mode	Byte Enum	0: create team, 1: remove team, 2: update team info; 3: add players to team; 4: remove players from team
			Team Display Name	Optional String	Only if Mode is 0 or 2.
			Team Prefix	Optional String	Only if Mode is 0 or 2. Displayed before the players' name that are part of this team.
			Team Suffix	Optional String	Only if Mode is 0 or 2. Displayed after the players' name that are part of this team.
			Friendly Fire	Optional Byte	Only if Mode is 0 or 2. 0 for off, 1 for on, 3 for seeing friendly invisibles.
			Name Tag Visibility	Optional String	Only if Mode is 0 or 2. always, hideForOtherTeams, hideForOwnTeam, never.
			Collision Rule	Optional String	Only if Mode is 0 or 2. always, hideForOtherTeams (sic), hideForOwnTeam (sic), never
			Color	Optional Byte	Only if Mode is 0 or 2. Same as Chat colors.
			Player Count	Optional VarInt	Only if Mode is 0 or 3 or 4. Number of players in the array.
			Players	Optional Array of String	Only if Mode is 0 or 3 or 4. Players to be added/remove from the team. Max 40 characters so may be uuid's later.

Sound Effect

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x47	Play	Client	Sound ID	VarInt	ID of hardcoded sound event (events)
			Sound Category	VarInt Enum	The category that this sound will be played from (current categories)
			Effect Position X	Int	Effect X multiplied by 8
			Effect Position Y	Int	Effect Y multiplied by 8
			Effect Position Z	Int	Effect Z multiplied by 8
			Volume	Float	1.0 is 100%, capped between 0.0 and 1.0 by vanilla client
			Pitch	Unsigned Byte	Float multiplied by 63.5, capped between 0.5 and 2.0 by vanilla client

Entity Properties

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x20 0x4B	Play	Client	Entity ID		VarInt
			Number Of Properties		Int		Number of elements in the following array
			Property	Key	Array	String	See below
				Value		Double	See below
				Number Of Modifiers		VarInt	Number of elements in the following array
				Modifiers		Array of Modifier Data	See Attribute#Modifiers. Modifier Data defined below.

Known Key values (see also Attribute#Modifiers):

Key	Default	Min	Max	Label
generic.maxHealth	20.0	0.0	Double.MaxValue 1024.0	Max Health
generic.followRange	32.0	0.0	2048.0	Follow Range
generic.knockbackResistance	0.0	0.0	1.0	Knockback Resistance
generic.movementSpeed	0.699999988079071	0.0	Double.MaxValue 1024.0	Movement Speed
generic.attackDamage	2.0	0.0	Double.MaxValue 2048.0	Attack Damage
generic.attackSpeed	4.0	0.0	1024.0	Attack Speed
horse.jumpStrength	0.7	0.0	2.0	Jump Strength
zombie.spawnReinforcements	0.0	0.0	1.0	Spawn Reinforcements Chance

Modifier Data structure:

Field Name	Field Type	Notes
UUID	UUID
Amount	Double
Operation	Byte

Map Chunk Bulk

Replaced by multiple Chunk Data packets.

Update Entity NBT

Wasn't used for anything.

Serverbound

Teleport Confirm

Sent by client as confirmation of Player Position And Look packet.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Play	Server	Teleport ID	VarInt

Tab-Complete

Sent when the user presses tab while writing text.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14 0x01	Play	Server	Text	String	All text behind the cursor (e.g. to the left of the cursor in left-to-right languages like English)
			Assume Command	Boolean	If true, the server will parse Text as a command even if it doesn't start with a /. Used in the command block GUI.
			Has Position	Boolean
			Looked At Block	Optional Position	The position of the block being looked at. Only sent if Has Position is true.

Client Status

Sent when the client is ready to complete login and when the client is ready to respawn after death.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x16 0x03	Play	Server	Action ID	VarInt Enum	See below

Action ID values:

Action ID	Action
0	Perform respawn
1	Request stats
2	Taking Inventory achievement Open Inventory

Client Settings

Sent when the player connects, or when settings are changed.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x15 0x04	Play	Server	Locale	String	e.g. en_GB
			View Distance	Byte	Client-side render distance, in chunks
			Chat Mode	Byte VarInt Enum	0: enabled, 1: commands only, 2: hidden
			Chat Colors	Boolean	“Colors” multiplayer setting
			Displayed Skin Parts	Unsigned Byte	Skin parts, see note below
			Main Hand	VarInt Enum	0: Left, 1: Right

Displayed Skin Parts flags:

• Bit 0 (0x01): Cape enabled
• Bit 1 (0x02): Jacket enabled
• Bit 2 (0x04): Left Sleeve enabled
• Bit 3 (0x08): Right Sleeve enabled
• Bit 4 (0x10): Left Pants Leg enabled
• Bit 5 (0x20): Right Pants Leg enabled
• Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Use Entity

This packet is sent from the client to the server when the client attacks or right-clicks another entity (a player, minecart, etc).

A Notchian server only accepts this packet if the entity being attacked/used is visible without obstruction and within a 4-unit radius of the player's position.

Note that middle-click in creative mode is interpreted by the client and sent as a Creative Inventory Action packet instead.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x02 0x0A	Play	Server	Target	VarInt
			Type	VarInt Enum	0: interact, 1: attack, 2: interact at
			Target X	Optional Float	Only if Type is interact at
			Target Y	Optional Float	Only if Type is interact at
			Target Z	Optional Float	Only if Type is interact at
			Hand	Optional VarInt Enum	Only if Type is interact or interact at; 0: main hand, 1: off hand

Vehicle Move (serverbound)

Sent when a player moves in a vehicle. Fields are the same as in Player Position And Look. Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x10	Play	Server	X	Double	Absolute position (X coordinate)
			Y	Double	Absolute position (Y coordinate)
			Z	Double	Absolute position (Z coordinate)
			Yaw	Float	Absolute rotation on the vertical Axis, in degrees
			Pitch	Float	Absolute rotation on the horizontal Axis, in degrees

Steer Boat

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x11	Play	Server	Boolean	Unknown
			Boolean	Unknown 2

Player Digging

Sent when the player mines a block. A Notchian server only accepts digging packets with coordinates within a 6-unit radius of the player's position.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x07 0x13	Play	Server	Status	Byte Enum	The action the player is taking against the block (see below)
			Location	Position	Block position
			Face	Byte Enum	The face being hit (see below)

Status can be one of seven values:

Value	Meaning	Notes
0	Started digging
1	Cancelled digging	Sent when the player lets go of the Mine Block key (default: left click)
2	Finished digging	Sent when the client thinks it is finished
3	Drop item stack	Triggered by using the Drop Item key (default: Q) with the modifier to drop the entire selected stack (default: depends on OS). Location is always set to 0/0/0, Face is always set to -Y.
4	Drop item	Triggered by using the Drop Item key (default: Q). Location is always set to 0/0/0, Face is always set to -Y.
5	Shoot arrow / finish eating	Location is always set to 0/0/0, Face is always set to Special.
6	Swap item in hand	Used to swap or assign an item to the second hand. Location is always set to 0/0/0, Face is always set to -Y.

The Face field can be one of the following values, representing the face being hit (or the Special value used for “shoot arrow / finish eating”):

Value	Offset	Face
0	-Y	Bottom
1	+Y	Top
2	-Z	North
3	+Z	South
4	-X	West
5	+X	East
255	—	Special

Entity Action

Sent at least when crouching, leaving a bed, or sprinting. To send action animation to client use 0x28. The client will send this with Action ID = 3 when “Leave Bed” is clicked.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0B 0x14	Play	Server	Entity ID	VarInt	Player ID
			Action ID	VarInt Enum	The ID of the action, see below
			Jump Boost	VarInt	Horse jump boost. Ranged from 0 to 100.

Action ID can be one of the following values:

ID	Action
0	Crouch
1	Uncrouch
2	Leave bed
3	Start sprinting
4	Stop sprinting
5	Start Jump with horse
6	Stop Jump with horse
7	Open ridden horse inventory
8	Start Elytra Flying

“Open inventory” is now sent via the Client Status packet.

Update Sign

This message is sent from the client to the server when the “Done” button is pushed after placing a sign.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x12 0x19	Play	Server	Location	Position	Block Coordinates
			Line 1	Chat String	First line of text in the sign
			Line 2	Chat String	Second line of text in the sign
			Line 3	Chat String	Third line of text in the sign
			Line 4	Chat String	Fourth line of text in the sign

Animation

Sent when the player's arm swings.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0A 0x1A	Play	Server	Hand	VarInt Enum	Hand used for the animation

Player Block Placement

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x08 0x1C	Play	Server	Location	Position	Block position
			Face	Byte VarInt Enum	The face on which the block is placed (as documented at Player Digging)
			Held Item	Slot
			Hand	VarInt Enum	The hand from which the block is placed; 0: main hand, 1: off hand
			Cursor Position X	Unsigned Byte	The position of the crosshair on the block, from 0 to 15 increasing from west to east
			Cursor Position Y	Unsigned Byte	The position of the crosshair on the block, from 0 to 15 increasing from bottom to top
			Cursor Position Z	Unsigned Byte	The position of the crosshair on the block, from 0 to 15 increasing from north to south

In normal operation (i.e. placing a block), this packet is sent once, with the values set normally.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to one 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 0–7) or as a top slab (values 8–15). The Cursor Position Z should be 15 since the player was looking at the southernmost part of the block.

This packet has a special case where X, Y, Z, and Direction are all -1. (Note that Y is unsigned so set to 255.) This special packet indicates that the currently held item for the player should have its state updated such as eating food, pulling back bows, using buckets, etc.

Special note on using buckets: When using buckets, the Notchian client might send two packets: first a normal and then a special case. The first normal packet is sent when you're looking at a block (e.g. the water you want to scoop up). This normal packet does not appear to do anything with a Notchian server. The second, special case packet appears to perform the action — based on current position/orientation and with a distance check — it appears that buckets can only be used within a radius of 6 units.

Use Item

Sent when pressing the Use Item key (default: right click) with an item in hand.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1D	Play	Server	Hand	VarInt Enum	Hand used for the animation

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.