Slot Data

The Slot data structure is how Minecraft represents an item and its associated data in the Minecraft Protocol.

Format

Name	Type	Meaning
Block ID	Short	The item/block ID. A value of -1 signifies that the slot is empty, and no further data follows.
Item Count	Optional Byte	Not present if Block ID is -1.
Item Damage	Optional Short	Not present if Block ID is -1.
NBT	Optional NBT	Not present if Block ID is -1. If 0, there is no NBT data, and no further data follows. Otherwise the byte is the start of an NBT blob as shown below:

  COMPOUND ''
    LIST 'StoredEnchantments'
      COMPOUND
        SHORT 'id'
        SHORT 'lvl'
      END
      COMPOUND
        ...
      END
      ...
    END
    INT 'Unbreakable'
    ...
  END

See NBT for more information about the NBT format, and here for the contained information and its format.

Examples

  ff ff                            | empty slot
  01 16 01 00 00 00                | a diamond pickaxe
  01 16 01 00 00 01 04 CA FE BA BE | a diamond pickaxe with (made-up) NBT data