Tag (item)

Tags are items exclusive to the 23w13a_or_b April Fools' joke snapshot from 2023. They are used to craft in-game representations of NBT tags.

Obtaining
In survival, a stonecutter can be used to cut a name tag into either 16 "Name" or 16 "Tag" items. These can be cut into 16 Bit items each.

Bits can be used in a crafting table to craft Left Curly, Right Curly, Left Square, and Right Square. In appears like these are the only tag items that can be crafted from Bits.

A crafting table can be used to convert a "Tag" item into a "Byte Tag." The amount of sticks added to the crafting recipe specifies the value of the Byte, as a signed 8-bit value. For example, a "Tag" and a full stack of sticks make a Byte with the value, while 254 sticks result in. Only one of the sticks is consumed. Two Bytes can be crafted into a "Short Tag" (equivalent to 16 bit), two Shorts into an "Int Tag" (equivalent to 32 bit), and two Ints into a "Long Tag" (equivalent to 64 bit). Many other combinations that form either 16, 32, or 64 bit are possible. For example, two Shorts and an Int make a Long. When combining values, their digits are stuck together in the given order, e.g.  and   make   (equivalent to 010016 in hexadecimal). Undoing any of these crafting actions in e.g. a stonecutter is not possible.

"Float" and "Double Tags" can be crafted by adding one or two boats to any numeric tag. A "String Tag" is crafted with a "Tag" and a piece of string.

"Name" and "String Tags" must be named in an anvil before they can be used. Unnamed Names and Strings always produce a "Sssyntax Error". None of the other tag items can be named.

All these items can be combined in a crafting table to form a short sequence of JSON code, as long as the resulting syntax is valid. For example:
 * A pair of Curlies that enclose a named "Name" item and some value, e.g. a Byte, create a "Compound Tag" with the content.
 * Because of the limited size of the crafting table only 3 name-value pairs can be put between Curlies at a time. Compound Tags of any length can be created by concatenating two or more Compound Tags.
 * An empty pair of Curlies produces an empty Compound Tag with the content.
 * A pair of Square brackets that enclose any number of values, e.g. 7 Bytes, create a "List Tag" with the content.
 * Because of the limited size of the crafting table only 7 values can be put between Square brackets at a time. List Tags of any length can be created by concatenating two or more List Tags.
 * An empty pair of Square brackets produces an empty List with the content.
 * "Name" items cannot be used in a List.

The resulting Compound and List Tags can be used as values in other Compound and List Tags, as deeply nested as you want.

Usage
Tags appear to have no further functionality. They cannot be eaten or placed in the world, except in an item frame, as each other item can. However, Compound Tags with values like  will show the enchantment glint and actually act accordingly when used. This appears to work with many weapon and tool enchantments.

Trivia

 * Even if not explicitly mentioned all this is obviously meant to create NBT tags with the game's crafting system.
 * This implies that a name tag is 128 bit.
 * The snapshot also contains an unused texture for an.