Difference between revisions of "Pre-release protocol"

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Revision as of 19:25, 9 April 2024

This page documents the changes from the last stable Minecraft release (currently 1.20.4, protocol 765) to the current pre-release (currently 24w13b, protocol Snapshot 182). 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

No changes so far.

Packets

ID Packet name Documentation
Handshake serverbound
0x00 Handshake Current Pre
Login clientbound
0x01 Encryption Request Current Pre
0x05 Cookie Request (login) Pre
Login serverbound
0x04 Cookie Response (login) Pre
Configuration clientbound
0x00 Cookie Request (configuration) Pre
0x00 0x01 Clientbound Plugin Message (configuration) Current (unchanged)
0x01 0x02 Disconnect (configuration) Current (unchanged)
0x02 0x03 Finish Configuration Current (unchanged)
0x03 0x04 Clientbound Keep Alive (configuration) Current (unchanged)
0x04 0x05 Ping (configuration) Current (unchanged)
0x06 Reset Chat Pre
0x05 0x07 Registry Data Current Pre
0x06 0x08 Remove Resource Pack (configuration) Current (unchanged)
0x07 0x09 Add Resource Pack (configuration) Current (unchanged)
0x0A Store Cookie (configuration) Pre
0x0B Transfer (configuration) Pre
0x08 0x0C Feature Flags Current (unchanged)
0x09 0x0D Update Tags (configuration) Current (unchanged)
0x0E Clientbound Known Packs Pre
Configuration serverbound
0x01 Cookie Response (configuration) Pre
0x01 0x02 Serverbound Plugin Message (configuration) Current (unchanged)
0x02 0x03 Finish Configuration Current (unchanged)
0x03 0x04 Serverbound Keep Alive (configuration) Current (unchanged)
0x04 0x05 Pong (configuration) Current (unchanged)
0x05 0x06 Resource Pack Response (configuration) Current (unchanged)
0x07 Serverbound Known Packs Pre
Play clientbound
0x16 Cookie Request (Play) Pre
0x16 0x17 Set Cooldown Current (unchanged)
0x17 0x18 Chat Suggestions Current (unchanged)
0x18 0x19 Clientbound Plugin Message (play) Current (unchanged)
0x19 0x1A Damage Event Current (unchanged)
0x1B Debug Sample Pre
0x1A 0x1C Delete Message Current (unchanged)
0x1B 0x1D Disconnect (play) Current (unchanged)
0x1C 0x1E Disguised Chat Message Current (unchanged)
0x1D 0x1F Entity Event Current (unchanged)
0x1E 0x20 Explosion Current (unchanged)
0x1F 0x21 Unload Chunk Current (unchanged)
0x20 0x22 Game Event Current (unchanged)
0x21 0x23 Open Horse Screen Current (unchanged)
0x22 0x24 Hurt Animation Current (unchanged)
0x23 0x25 Initialize World Border Current (unchanged)
0x24 0x26 Clientbound Keep Alive (play) Current (unchanged)
0x25 0x27 Chunk Data and Update Light Current (unchanged)
0x26 0x28 World Event Current (unchanged)
0x27 0x29 Particle Current (unchanged)
0x28 0x2A Update Light Current (unchanged)
0x29 0x2B Login (play) Current Pre
0x2A 0x2C Map Data Current (unchanged)
0x2B 0x2D Merchant Offers Current (unchanged)
0x2C 0x2E Update Entity Position Current (unchanged)
0x2D 0x2F Update Entity Position and Rotation Current (unchanged)
0x2E 0x30 Update Entity Rotation Current (unchanged)
0x2F 0x31 Move Vehicle Current (unchanged)
0x30 0x32 Open Book Current (unchanged)
0x31 0x33 Open Screen Current (unchanged)
0x32 0x34 Open Sign Editor Current (unchanged)
0x33 0x35 Ping (play) Current (unchanged)
0x34 0x36 Ping Response (play) Current (unchanged)
0x35 0x37 Place Ghost Recipe Current (unchanged)
0x36 0x38 Player Abilities Current (unchanged)
0x37 0x39 Player Chat Message Current (unchanged)
0x38 0x3A End Combat Current (unchanged)
0x39 0x3B Enter Combat Current (unchanged)
0x3A 0x3C Combat Death Current (unchanged)
0x3B 0x3D Player Info Remove Current (unchanged)
0x3C 0x3E Player Info Update Current (unchanged)
0x3D 0x3F Look At Current (unchanged)
0x3E 0x40 Synchronize Player Position Current (unchanged)
0x3F 0x41 Update Recipe Book Current (unchanged)
0x40 0x42 Remove Entities Current (unchanged)
0x41 0x43 Remove Entity Effect Current (unchanged)
0x42 0x44 Reset Score Current (unchanged)
0x43 0x45 Remove Resource Pack (play) Current (unchanged)
0x44 0x46 Add Resource Pack (play) Current (unchanged)
0x45 0x47 Respawn Current Pre
0x46 0x48 Set Head Rotation Current (unchanged)
0x47 0x49 Update Section Blocks Current (unchanged)
0x48 0x4A Select Advancements Tab Current (unchanged)
0x49 0x4B Server Data Current (unchanged)
0x4A 0x4C Set Action Bar Text Current (unchanged)
0x4B 0x4D Set Border Center Current (unchanged)
0x4C 0x4E Set Border Lerp Size Current (unchanged)
0x4D 0x4F Set Border Size Current (unchanged)
0x4E 0x50 Set Border Warning Delay Current (unchanged)
0x4F 0x51 Set Border Warning Distance Current (unchanged)
0x50 0x52 Set Camera Current (unchanged)
0x51 0x53 Set Held Item Current (unchanged)
0x52 0x54 Set Center Chunk Current (unchanged)
0x53 0x55 Set Render Distance Current (unchanged)
0x54 0x56 Set Default Spawn Position Current (unchanged)
0x55 0x57 Display Objective Current (unchanged)
0x56 0x58 Set Entity Metadata Current (unchanged)
0x57 0x59 Link Entities Current (unchanged)
0x58 0x5A Set Entity Velocity Current (unchanged)
0x59 0x5B Set Equipment Current (unchanged)
0x5A 0x5C Set Experience Current (unchanged)
0x5B 0x5D Set Health Current (unchanged)
0x5C 0x5E Update Objectives Current (unchanged)
0x5D 0x5F Set Passengers Current (unchanged)
0x5E 0x60 Update Teams Current (unchanged)
0x5F 0x61 Update Score Current (unchanged)
0x60 0x62 Set Simulation Distance Current (unchanged)
0x61 0x63 Set Subtitle Text Current (unchanged)
0x62 0x64 Update Time Current (unchanged)
0x63 0x65 Set Title Text Current (unchanged)
0x64 0x66 Set Title Animation Times Current (unchanged)
0x65 0x67 Entity Sound Effect Current (unchanged)
0x66 0x68 Sound Effect Current (unchanged)
0x67 0x69 Start Configuration Current (unchanged)
0x68 0x6A Stop Sound Current (unchanged)
0x6B Store Cookie (Play) Pre
0x69 0x6C System Chat Message Current (unchanged)
0x6A 0x6D Set Tab List Header And Footer Current (unchanged)
0x6B 0x6E Tag Query Response Current (unchanged)
0x6C 0x6F Pickup Item Current (unchanged)
0x6D 0x70 Teleport Entity Current (unchanged)
0x6E 0x71 Set Ticking State Current (unchanged)
0x6F 0x72 Step Tick Current (unchanged)
0x73 Transfer (Play) Pre
0x70 0x74 Update Advancements Current (unchanged)
0x71 0x75 Update Attributes Current Pre
0x72 0x76 Entity Effect Current Pre
0x73 0x77 Update Recipes Current (unchanged)
0x74 0x78 Update Tags (play) Current (unchanged)
Play serverbound
0x04 Chat Command Current Pre
0x05 Signed Chat Command Pre
0x05 0x06 Chat Message Current (unchanged)
0x06 0x07 Player Session Current (unchanged)
0x07 0x08 Chunk Batch Received Current (unchanged)
0x08 0x09 Client Status Current (unchanged)
0x09 0x0A Client Information (play) Current (unchanged)
0x0A 0x0B Command Suggestions Request Current (unchanged)
0x0B 0x0C Acknowledge Configuration Current (unchanged)
0x0C 0x0D Click Container Button Current (unchanged)
0x0D 0x0E Click Container Current (unchanged)
0x0E 0x0F Close Container Current (unchanged)
0x0F 0x10 Change Container Slot State Current (unchanged)
0x11 Cookie Response (play) Pre
0x10 0x12 Serverbound Plugin Message (play) Current (unchanged)
0x13 Debug Sample Subscription Pre
0x11 0x14 Edit Book Current (unchanged)
0x12 0x15 Query Entity Tag Current (unchanged)
0x13 0x16 Interact Current (unchanged)
0x14 0x17 Jigsaw Generate Current (unchanged)
0x15 0x18 Serverbound Keep Alive (play) Current (unchanged)
0x16 0x19 Lock Difficulty Current (unchanged)
0x17 0x1A Set Player Position Current (unchanged)
0x18 0x1B Set Player Position and Rotation Current (unchanged)
0x19 0x1C Set Player Rotation Current (unchanged)
0x1A 0x1D Set Player On Ground Current (unchanged)
0x1B 0x1E Move Vehicle Current (unchanged)
0x1C 0x1F Paddle Boat Current (unchanged)
0x1D 0x20 Pick Item Current (unchanged)
0x1E 0x21 Ping Request (play) Current (unchanged)
0x1F 0x22 Place Recipe Current (unchanged)
0x20 0x23 Player Abilities Current (unchanged)
0x21 0x24 Player Action Current (unchanged)
0x22 0x25 Player Command Current (unchanged)
0x23 0x26 Player Input Current (unchanged)
0x24 0x27 Pong (play) Current (unchanged)
0x25 0x28 Change Recipe Book Settings Current (unchanged)
0x26 0x29 Set Seen Recipe Current (unchanged)
0x27 0x2A Rename Item Current (unchanged)
0x28 0x2B Resource Pack Response (play) Current (unchanged)
0x29 0x2C Seen Advancements Current (unchanged)
0x2A 0x2D Select Trade Current (unchanged)
0x2B 0x2E Set Beacon Effect Current (unchanged)
0x2C 0x2F Set Held Item Current (unchanged)
0x2D 0x30 Program Command Block Current (unchanged)
0x2E 0x31 Program Command Block Minecart Current (unchanged)
0x2F 0x32 Set Creative Mode Slot Current (unchanged)
0x30 0x33 Program Jigsaw Block Current (unchanged)
0x31 0x34 Program Structure Block Current (unchanged)
0x32 0x35 Update Sign Current (unchanged)
0x33 0x36 Swing Arm Current (unchanged)
0x34 0x37 Teleport To Entity Current (unchanged)
0x35 0x38 Use Item On Current (unchanged)
0x36 0x39 Use Item Current (unchanged)

New/modified data types

No changes so far.

Entity Metadata

Type Name Value Notes
0 Byte Byte
1 VarInt VarInt
2 VarLong VarLong
3 Float Float
4 String String
5 Text Component Text Component
6 Optional Text Component (Boolean, Optional Text Component) Text Component is present if the Boolean is set to true.
7 Slot Slot
8 Boolean Boolean
9 Rotations (Float, Float, Float) rotation on x, rotation on y, rotation on z
10 Position Position
11 Optional Position (Boolean, Optional Position) Position is present if the Boolean is set to true.
12 Direction VarInt Enum Down = 0, Up = 1, North = 2, South = 3, West = 4, East = 5
13 Optional UUID (Boolean, Optional UUID) UUID is present if the Boolean is set to true.
14 Block State VarInt An ID in the block state registry.
15 Optional Block State VarInt 0 for absent (air is unrepresentable); otherwise, an ID in the block state registry.
16 NBT NBT
17 Particle (VarInt, Varies) particle type (an ID in the minecraft:particle_type registry), particle data (See Particles.)
18 Particles (VarInt, Array of Particle) length of array, particle data (See directly above.)
18 19 Villager Data (VarInt, VarInt, VarInt) villager type, villager profession, level (See below.)
19 20 Optional VarInt VarInt 0 for absent; 1 + actual value otherwise. Used for entity IDs.
20 21 Pose VarInt Enum STANDING = 0, FALL_FLYING = 1, SLEEPING = 2, SWIMMING = 3, SPIN_ATTACK = 4, SNEAKING = 5, LONG_JUMPING = 6, DYING = 7, CROAKING = 8, USING_TONGUE = 9, SITTING = 10, ROARING = 11, SNIFFING = 12, EMERGING = 13, DIGGING = 14, SLIDING = 15, SHOOTING = 16, INHALING = 17
21 22 Cat Variant VarInt An ID in the minecraft:cat_variant registry.
22 23 Wolf Variant VarInt An ID in the minecraft:wolf_variant registry.
22 24 Frog Variant VarInt An ID in the minecraft:frog_variant registry.
23 25 Optional Global Position (Boolean, Optional Identifier, Optional Position) dimension identifier, position; only if the Boolean is set to true.
24 26 Painting Variant VarInt An ID in the minecraft:painting_variant registry.
25 27 Sniffer State VarInt Enum IDLING = 0, FEELING_HAPPY = 1, SCENTING = 2, SNIFFING = 3, SEARCHING = 4, DIGGING = 5, RISING = 6
26 28 Armadillo State VarInt Enum IDLE = 0, ROLLING = 1, SCARED = 2
26 29 Vector3 (Float, Float, Float) x, y, z
27 30 Quaternion (Float, Float, Float, Float) x, y, z, w

Living Entity

TODO: This has changed to use the PARTICLES attribute

Wolf

Extends Tameable Animal.Inherited entity Tameable Animal does not existInherited entity Tameable Animal does not exist

Index Type Meaning Default
0 Wolf Variant (22 23) Wolf Variant PALE
1 Boolean (8) Is begging false
2 VarInt (1) Collar color (values are those used with dyes) 14 (Red)
3 VarInt (1) Anger time 0

Armadillo

Extends Animal.

Index Type Meaning Default
17 Armadillo State (26 28) Armadillo State IDLE

Block Actions

No changes so far.

Inventories

No changes so far.

Plugin Channels

No changes so far.

Handshake

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 765 in Minecraft 1.20.4).
Server Address String (255) Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information. Note that SRV records are a simple redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide example.org as server address in addition to connecting to it.
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, 3 for Transfer.

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

Encryption Request

Packet ID State Bound To Field Name Field Type Notes
0x01 Login Client Server ID String (20) Appears to be empty.
Public Key Length VarInt Length of Public Key.
Public Key Byte Array The server's public key, in bytes.
Verify Token Length VarInt Length of Verify Token. Always 4 for Notchian servers.
Verify Token Byte Array A sequence of random bytes generated by the server.
Should Authenticate Boolean

Cookie Request (login)

Requests a cookie that was previously stored.

Packet ID State Bound To Field Name Field Type Notes
0x05 Login Client Key Identifier The identifier of the cookie.

Serverbound

Cookie Response (login)

Response to a Cookie Request (login) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x04 Login Server Key Identifier The identifier of the cookie.
Has Payload Boolean The payload is only present if the cookie exists on the client.
Payload Length VarInt Length of the following byte array.
Payload Optional Byte Array (5120) The data of the cookie, if any.

Configuration

Clientbound

Cookie Request (configuration)

Requests a cookie that was previously stored.

Packet ID State Bound To Field Name Field Type Notes
0x00 Configuration Client Key Identifier The identifier of the cookie.

Reset Chat

Packet ID State Bound To Field Name Field Type Notes
0x06 Configuration Client no fields

Registry Data

Represents certain registries that are sent from the server and are applied on the client. The packet is sent for each of the following registries: minecraft:worldgen/biome, minecraft:chat_type, minecraft:trim_pattern, minecraft:trim_material, minecraft:wolf_variant, minecraft:dimension_type, minecraft:damage_type, and minecraft:banner_pattern.

Packet ID State Bound To Field Name Field Type Notes
0x07 Configuration Client Registry Codec NBT (Compound) See Registry Data.
Registry ID Identifier
Entry Count VarInt Number of entries in the following array.
Entries Entry ID Array Identifier
Has Data Boolean Whether the entry has any data following.
Data NBT Tag Entry data. Only present if Has Data is true.

Store Cookie (configuration)

Stores some arbitrary data on the client, which persists between server transfers. The Notchian client only accepts cookies of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x0A Configuration Client Key Identifier The identifier of the cookie.
Payload ByteArray(5120) The data of the cookie.

Transfer (configuration)

Notifies the client that it should transfer to the given server. Cookies previously stored are preserved between server transfers.

Packet ID State Bound To Field Name Field Type Notes
0x0B Configuration Client Host String The hostname of IP of the server.
Port VarInt The port of the server.

Clientbound Known Packs

Packet ID State Bound To Field Name Field Type Notes
0x0E Configuration Client Known Pack Count VarInt The number of known packs in the following array.
Known Packs Namespace Array String
ID String
Version String

Serverbound

Cookie Response (configuration)

Response to a Cookie Request (configuration) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x01 Configuration Server Key Identifier The identifier of the cookie.
Has Payload Boolean The payload is only present if the cookie exists on the client.
Payload Length VarInt Length of the following byte array.
Payload Optional Byte Array (5120) The data of the cookie, if any.

Serverbound Known Packs

ID 0x07, same structure as Clientbound Known Packs. If the client specifies a pack in this packet, the server should omit its contained data from Registry Data.

Play

Clientbound

Cookie Request (play)

Requests a cookie that was previously stored.

Packet ID State Bound To Field Name Field Type Notes
0x16 Play Client Key Identifier The identifier of the cookie.

Debug Sample

Packet ID State Bound To Field Name Field Type Notes
0x1B Play Client Sample Length VarInt The length of the following array.
Sample Long Array TODO: What is the structure of the data in this array?
Sample Type VarInt Enum The type of sample data. Currently always 0 (TICK_TIME).

Login (play)

Packet ID State Bound To Field Name Field Type Notes
0x2B Play Client Entity ID Int The player's Entity ID (EID).
Is hardcore Boolean
Dimension Count VarInt Size of the following array.
Dimension Names Array of Identifier Identifiers for all dimensions on the server.
Max Players VarInt Was once used by the client to draw the player list, but now is ignored.
View Distance VarInt Render distance (2-32).
Simulation Distance VarInt The distance that the client will process specific things, such as entities.
Reduced Debug Info Boolean If true, a Notchian client shows reduced information on the debug screen. For servers in development, this should almost always be false.
Enable respawn screen Boolean Set to false when the doImmediateRespawn gamerule is true.
Do limited crafting Boolean Whether players can only craft recipes they have already unlocked. Currently unused by the client.
Dimension Type Identifier VarInt The ID of the type of dimension in the minecraft:dimension_type registry, defined by the Registry Data packet.
Dimension Name Identifier Name of the dimension being spawned into.
Hashed seed Long First 8 bytes of the SHA-256 hash of the world's seed. Used client side for biome noise
Game mode Unsigned Byte 0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
Previous Game mode Byte -1: Undefined (null), 0: Survival, 1: Creative, 2: Adventure, 3: Spectator. The previous game mode. Vanilla client uses this for the debug (F3 + N & F3 + F4) game mode switch. (More information needed)
Is Debug Boolean True if the world is a debug mode world; debug mode worlds cannot be modified and have predefined blocks.
Is Flat Boolean True if the world is a superflat world; flat worlds have different void fog and a horizon at y=0 instead of y=63.
Has death location Boolean If true, then the next two fields are present.
Death dimension name Optional Identifier Name of the dimension the player died in.
Death location Optional Position The location that the player died at.
Portal cooldown VarInt The number of ticks until the player can use the portal again.
Enforces Secure Chat Boolean

Respawn

Packet ID State Bound To Field Name Field Type Notes
0x47 Play Client Dimension Type Identifier VarInt The ID of the type of dimension in the minecraft:dimension_type registry, defined by the Registry Data packet.
Dimension Name Identifier Name of the dimension being spawned into.
Hashed seed Long First 8 bytes of the SHA-256 hash of the world's seed. Used client side for biome noise
Game mode Unsigned Byte 0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
Previous Game mode Byte -1: Undefined (null), 0: Survival, 1: Creative, 2: Adventure, 3: Spectator. The previous game mode. Vanilla client uses this for the debug (F3 + N & F3 + F4) game mode switch. (More information needed)
Is Debug Boolean True if the world is a debug mode world; debug mode worlds cannot be modified and have predefined blocks.
Is Flat Boolean True if the world is a superflat world; flat worlds have different void fog and a horizon at y=0 instead of y=63.
Has death location Boolean If true, then the next two fields are present.
Death dimension Name Optional Identifier Name of the dimension the player died in.
Death location Optional Position The location that the player died at.
Portal cooldown VarInt The number of ticks until the player can use the portal again.
Data kept Byte Bit mask. 0x01: Keep attributes, 0x02: Keep metadata. Tells which data should be kept on the client side once the player has respawned.

In the Notchian implementation, this is context dependent:

  • normal respawns (after death) keep no data;
  • exiting the end poem/credits keeps the attributes;
  • other dimension changes (portals or teleports) keep all data.

Store Cookie (play)

Stores some arbitrary data on the client, which persists between server transfers. The Notchian client only accepts cookies of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x6B Play Client Key Identifier The identifier of the cookie.
Payload Length VarInt Length of the following byte array.
Payload Byte Array (5120) The data of the cookie.

Transfer (play)

Notifies the client that it should transfer to the given server. Cookies previously stored are preserved between server transfers.

Packet ID State Bound To Field Name Field Type Notes
0x73 Play Client Host String The hostname of IP of the server.
Port VarInt The port of the server.

Update Attributes

Sets attributes on the given entity.

Packet ID State Bound To Field Name Field Type Notes
0x71 Play Client Entity ID VarInt
Number Of Properties VarInt Number of elements in the following array.
Property Key Id Array Identifier VarInt Enum 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):

These changed between 24w03b and 24w13a, TODO: Update this

Id Key Default Min Max Label
0 generic.armor 0.0 0.0 30.0 Armor.
1 generic.armor_toughness 0.0 0.0 20.0 Armor Toughness.
2 generic.attack_damage 2.0 0.0 2048.0 Attack Damage.
3 generic.attack_knockback 0.0 0.0 5.0 Attack Knockback.
4 generic.attack_speed 4.0 0.0 1024.0 Attack Speed.
5 generic.block_interaction_range 4.5 0.0 64.0 Block Interaction Range.
6 generic.entity_interaction_range 3.0 0.0 64.0 Entity Interaction Range.
7 generic.flying_speed 0.4 0.0 1024.0 Flying Speed.
8 generic.follow_range 32.0 0.0 2048.0 Follow Range.
9 horse.jump_strength 0.7 0.0 2.0 Jump Strength.
10 generic.knockback_resistance 0.0 0.0 1.0 Knockback Resistance.
11 generic.luck 0.0 -1024.0 1024.0 Luck.
12 generic.max_absorption 0.0 0.0 2048.0 Max Absorption.
13 generic.max_health 20.0 1.0 1024.0 Max Health.
14 generic.movement_speed 0.7 0.0 1024.0 Movement Speed.
15 generic.scale 1.0 0.0625 16.0 Scale.
16 zombie.spawn_reinforcements 0.0 0.0 1.0 Spawn Reinforcements Chance.
17 generic.step_height 0.6 0.0 10.0 Step Height.

Modifier Data structure:

Field Name Field Type Notes
UUID UUID
Amount Double May be positive or negative.
Operation Byte See below.

The operation controls how the base value of the modifier is changed.

  • 0: Add/subtract amount
  • 1: Add/subtract amount percent of the current value
  • 2: Multiply by amount percent

All of the 0's are applied first, and then the 1's, and then the 2's.

Entity Effect

Packet ID State Bound To Field Name Field Type Notes
0x72 Play Client Entity ID VarInt
Effect ID VarInt See this table.
Amplifier Byte Notchian client displays effect level as Amplifier + 1.
Duration VarInt Duration in ticks. (-1 for infinite)
Flags Byte Bit field, see below.
Has Factor Data Boolean Used in DARKNESS effect
Factor Codec NBT Tag See below
Huh.png The following information needs to be added to this page:
What exact effect does the blend bit flag have on the client? What happens if it is used on effects besides DARKNESS?

Within flags:

  • 0x01: Is ambient - was the effect spawned from a beacon? All beacon-generated effects are ambient. Ambient effects use a different icon in the HUD (blue border rather than gray). If all effects on an entity are ambient, the "Is potion effect ambient" living metadata field should be set to true. Usually should not be enabled.
  • 0x02: Show particles - should all particles from this effect be hidden? Effects with particles hidden are not included in the calculation of the effect color, and are not rendered on the HUD (but are still rendered within the inventory). Usually should be enabled.
  • 0x04: Show icon - should the icon be displayed on the client? Usually should be enabled.
  • 0x08: Blend - should the effect's hard-coded blending be applied? Currently only used in the DARKNESS effect to apply extra void fog and adjust the gamma value for lighting.

Factor Data

Name Type Notes
padding_duration TAG_INT
factor_start TAG_FLOAT
factor_target TAG_FLOAT
factor_current TAG_FLOAT
effect_changed_timestamp TAG_INT
factor_previous_frame TAG_FLOAT
had_effect_last_tick TAG_BOOLEAN

Serverbound

Chat Command

Packet ID State Bound To Field Name Field Type Notes
0x04 Play Server Command String (256) The command typed by the client.
Timestamp Long The timestamp that the command was executed.
Salt Long The salt for the following argument signatures.
Array length VarInt Number of entries in the following array. The maximum length in Notchian server is 8.
Array of argument signatures Argument name Array (8) String (16) The name of the argument that is signed by the following signature.
Signature Byte Array (256) The signature that verifies the argument. Always 256 bytes and is not length-prefixed.
Message Count VarInt
Acknowledged Fixed BitSet (20)


Signed Chat Command

Packet ID State Bound To Field Name Field Type Notes
0x05 Play Server Command String(256) The command typed by the client.
Timestamp Long The timestamp that the command was executed. Milliseconds since the Unix epoch.
Salt Long The salt for the following argument signatures.
Argument Signature Count VarInt Number of elements in the following array. The maximum length in Notchian server is 8.
Argument Signatures Name Array String(16) The name of the argument that is signed by the following signature.
Signature ByteArray(256) The signature that verifies the argument. Always 256 bytes and is not length-prefixed.
Seen Messages Offset VarInt
Seen Messages Acknowledged Fixed BitSet(20)

Cookie Response (play)

Response to a Cookie Request (play) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x11 Play Server Key Identifier The identifier of the cookie.
Has Payload Boolean The payload is only present if the cookie exists on the client.
Payload Length Optional VarInt Length of the following byte array.
Payload Optional Byte Array (5120) The data of the cookie, if any.

Debug Sample Subscription

Packet ID State Bound To Field Name Field Type Notes
0x13 Play Server Sample Type VarInt Enum The type of debug sample to subscribe to. Currently always 0 (TICK_TIME).