Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.4.6, protocol 51) to the current pre-release (or weekly release). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

New Packets

Create Scoreboard (0xCE)

Server to Client

This is sent to the client when it should create a new scoreboard or remove one.

Packet ID	Field Name	Field Type	Example	Notes
0xCE	Scoreboard Name	string	deaths	An unique name for the scoreboard.
	Scoreboard Display Text	string	Deaths	The text to be displayed for the score.
	Create/Remove	byte	0	0 to create the scoreboard. 1 to remove the scoreboard .
Total Size:	5 bytes + length of string

Update Score (0xCF)

Server to Client

This is sent to the client when it should update a scoreboard item.

Packet ID	Field Name	Field Type	Example	Notes
0xCF	Item Name	string	Bob	An unique name to be displayed in the list.
	Update/Remove	byte	0	0 to create/update an item. 1 to remove an item.
	Score Name	string	deaths	The unique name for the scoreboard to be updated. Only sent to Update/Remove equals 0.
	Value	integer	5	The score to be displayed next to the entry. Only sent to Update/Remove equals 0.
Total Size:	9 bytes + length of strings

Display Scoreboard (0xD0)

Server to Client

This is sent to the client when it should display a scoreboard.

Packet ID	Field Name	Field Type	Example	Notes
0xD0	Position	byte	1	The position of the scoreboard. 0 = list, 1 = sidebar, 2 = belowName.
	Score Name	string	deaths	The unique name for the scoreboard to be displayed.
Total Size:	3 bytes + length of string

Teams (0xD1)

Server to Client

Creates and updates teams.

Packet ID	Field Name	Field Type	Example	Notes
0xD1	Team Name	string	mcdevs	An unique name for the team. (Shared with scoreboard).
	Mode	byte	0	If 0 then the team is created. If 1 then the team is removed. If 2 the team team information is updated. If 3 then new players are added to the team. If 4 then players are removed from the team.
	Team Display Name	string	McDevs	Only if Mode = 0 or 2.
	Team Prefix	string		Only if Mode = 0 or 2. Displayed before the players' name that are part of this team.
	Team Suffix	string		Only if Mode = 0 or 2. Displayed after the players' name that are part of this team.
	Friendly fire	bool	false	Only if Mode = 0 or 2.
	Player count	short	0	Only if Mode = 0 or 3 or 4. Number of players in the array
	Players	Array of strings		Only if Mode = 0 or 3 or 4. Players to be added/remove from the team.
Total Size:	Variable

Changed Packets

Open Window (0x64)

Server to Client

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.

Packet ID	Field Name	Field Type	Example	Notes
0x64	Window id	byte	123	A unique id number for the window to be displayed. Notchian server implementation is a counter, starting at 1.
	Inventory Type	byte	2	The window type to use for display. Check below
	Window title	string	Chest	The title of the window.
	Number of Slots	byte	3	Number of slots in the window (excluding the number of slots in the player inventory).
	Use provided window title	boolean	1	If false, the client will look up a string like "window.minecart". If true, the client uses what the server provides.
Total Size:	6 bytes + length of string

Changed Data Types

Entity Metadata

Mobs

Index 5, string: Mob Name

The name to be displayed on the nameplate above the entity (If Show nameplate = 1).

Index 6, byte: Show nameplate

Set to 1 to show the nameplate, otherwise it is not displayed.

Minecart

Index 20, int: Block id & metadata

The id and metadata of the block to be shown in the minecart (If Show block = 1).

The block id can be obtained by: value & 0xFFFF.

The block metadata can be obtained by: value >> 16.

Index 21, int: Block position

The position (Y axis) of the block in the minecart. (Default: 6)

Index 22, byte: Show block

Set to 1 to show the block in the minecart, otherwise the block is not displayed.

Removed Packets

-None-

Protocol History

13w06a: Protocol version is now 57.

13w05a: Protocol version is now 56. New packets for teams.

13w04a: Protocol version is now 55. New packets for scoreboards.

13w03a: Protocol version is now 54.

13w02a: Protocol version is now 53. All Minecart entities use object type 10, and send the block within seperately. Minecarts now send their type as object data in 0x17. Added boolean to 0x64 (Open Window) to determine whether or not to use the provided window title.