Java Edition:Long Name Item

Long Name.PNG

Long Name Item
Item with an 81 character name
Type	Item
Version Preparation
Pre-upgrade Range	12w41a - 17w50a
Post-upgrade Range	18w21b - 18w22a

This article is a work in progress. 

Please help in the creation of this article/section by expanding or improving it.
To do: Add downgrade version range; link to discord discussion

By updating a custom named item through certain versions will add additional characters, which can make the name longer than usually possible. You can also give items a longer name than possible by downgrading the custom named item.

Obtaining

Upgrading

Warning: Upgrading 

This feature uses upgrading and requires specific version paths. Follow the page instructions carefully.

Obtaining this is very simple by updating your world.

1. First, get a custom named item from 12w41a (1.4.2 snapshot) through 17w50a (1.13 snapshot).
2. Store the item in a regular chest. This does not work if the item is in your inventory or an ender chest.
3. Directly update this item to (or stored in unloaded chunks until) 18w21b/18w22a.

This adds additional characters to the custom name.

Note: This also works with translatable items, such as woodland mansion explorer maps and ocean monument explorer maps. In addition, you can get long names for all renamed mobs in the game except for the ender dragon. This is also possible in current versions by giving a Name Tag a long name.

Downgrading

Warning: Downgrading 

This feature uses downgrading which can result in crashes, data loss, or corruption, and requires specific versions. Follow the page instructions carefully.

If you downgrade to before 17w50a and upgrade back to 18w21b/18w22a, the name will increase again. With this method, the player can obtain an item with a name length of 65,524. Going beyond this limit will cause errors while saving the string to NBT. The growth is exponential due to the automatic addition of 4 double quotes with every trip to 18w21b/18w22a. For an unknown reason, when the player has the item in their inventory, the name gets longer when the player downgrades back to 17w50a.

Caution! - As the item's name increases, the game starts lagging more and more when the item's tool tip is rendered.

The maximum number of characters after a number of downgrades (needs updating, using / is faster than using &)

• 0 - 221
• 1 - 310
• 2 - 485
• 3 - 832
• 4 - 1,523
• 5 - 2,902
• 6 - 5,657
• 7 - 11,164
• 8 - 22,175
• 9 - 44,194
• 10 - 88,229
• 11 - 176,296
• 12 - 352,427
• 13 - 704,686
• 14 - 1,409,201
• 15 - 2,818,228

Formula for Calculation of Name Length

$L=(B+4)2^{D}+C(2^{\mid D-1\mid }+3(D-1-\mid D-1\mid )+5)+A+7D-4$
A = Number of Normal Characters
B = Number of Backslashes/Quotation Marks
C = Number of (</>/'/=/&)
D = Number of Downgrades/Updates to 18w21b/18w22a

Characters

Different characters convert to different characters upon updating.

All custom named items have {"text":"" added to the beginning of the name, and ""} added to the end of the name. This causes all custom named items to look like this: {"text":"<previous name>"}.

Using this method alone, along with previously naming the item with all 35 characters allows for a custom name of 46 characters. This is 11 more than the maximum.

The translations for the woodland mansion maps and ocean explorer maps are also unique. Woodland mansion maps convert to {"translate":"filled_map.mansion"} and ocean explorer maps convert to {"translate":"filled_map.monument"}.

These maps are interesting, because this name conversion also applies to villagers, meaning they can trade these broken maps in later versions. Other specific characters affected are below. The best possible combination of characters would be 35 of any of these characters <>='& which would result in a total of 221 characters.

• A backslash \ becomes \\.
• A double quote " becomes \".
• A greater than symbol > becomes \u003e.
• A less than symbol < becomes \u003c.
• An equal sign symbol = becomes \u003d.
• An and symbol & becomes \u0026.
• A single quote ' becomes \u0027.

See also

• Long Name Mob
• Long Sign
• Long World Name
• Nameless Item