Sign

Signs are blocks that allow text to be input on one side of them. Although signs are primarily used for text related purposes, due to being a non-solid block, they may be used to block the flow of liquids whilst allowing players to traverse back and forth. Signs are also often used for aesthetic purposes, such as to create the sides of chairs or ends of beds.

Signs are one of the many blocks that are broken more quickly with a sword, but still deal double damage to the sword. They can be broken much faster with an axe.

Properties
Signs count as a regular block, except mobs and items can pass through them. This means that other blocks can be placed on top of a sign, and wall-clinging blocks can also be placed on their sides. This also means that mobs will recognize them as solid and try to walk over them even if the signs are placed over high drops, which makes convincing mobs to fall down high drops (such as in mob traps) convenient. With the 12w04a snapshot, however, they seem to recognize signs as non-solid, and will avoid walking over them if the drop below is too tall.

Any kind of liquid cannot enter the space occupied by a sign, so signs, like ladders, may be used to make a doorway through which lava and water cannot flow.

Text editing interface
After placing a sign, a window pops up where the player may input text to be placed on the sign, although signs may also be left blank. Four lines of text are available, with 15 characters on each line. To switch between lines, the player can press Enter or the up/down arrow keys. The line which is currently selected will have a greater-than and less-than sign (> and <) at the beginning and end of it, respectively. While editing, within a single line text can only be entered and deleted in an ordinal manner, meaning that it is impossible to insert text in the middle of an already typed line - the player must delete and reenter text in order to make edits. Once a line has 15 characters, no more text may be entered on that line.

After the editing window is closed, the sign's text may only be changed by removing it (which will discard the text) and placing it again. In singleplayer, the game pauses until the player finishes typing.

The Xbox 360 Edition supports both the Xbox 360 on-screen keyboard and direct editing of text using a USB keyboard or controller chatpad. In online mode, the sign text is subject to word-filtering. After text is entered, the signs say "Awaiting approval" on all four lines while wordfilter is being run, after which the text appears. (In early versions, the message was also shown while text was being input, and sometimes it was shown persistently as a result of a glitch.) If the sign text contains any inappropriate language, all lines read "Censored".

Placement
The player can place signs sticking out of the ground, or on walls without any post grounding them. Signs may be placed attached to any block whatsoever, including ones such as fences, glass, other signs, and minecart tracks, which torches cannot be attached to (except to fences in Beta 1.7.2 and above). As of version 1.4.6, signs may be placed on chests by sneaking during placement.

Free-standing signs can face one of 16 directions, and face toward the player when placed. Wall-mounted signs can only face the four cardinal directions, and are attached to the face the player clicks on of an existing block.

If a sign is placed underwater, either on the side of a block or on top of another sign, an air bubble will form, allowing the player to breathe underwater.

Colored text


The text in signs can be colored. The section sign (§) will change the color of the following text on the current line. The section sign can not be entered via Minecraft itself; a map editor is required to edit the text to enter the § character.

Bugs

 * In SMP, if a player is editing a sign and another player teleports that player away, he is still able to edit the sign "remotely".
 * In SMP, if a player destroys a placed sign while another player is writing on it, the text prompt will not disappear.
 * Like paintings, signs do not use the Smooth Lighting function when enabled.
 * If a player enters all fifteen characters on a line as tildes (~), the first and last two tildes appear in mid-air, instead of on the sign. This also occurs with a line of 15 "at" symbols (@).
 * The grave character (`) and tilde + letter (ã, õ) cannot be typed on a sign.
 * If a sign is placed during the portal animation, the text prompt will not appear.
 * In multiplayer, when players do not have permission to remove a sign, they can still delete the text by destroying it, after which the sign will come back, but blank. This is client-side, however, and the text reappears after disconnecting and reconnecting.
 * In multiplayer, if a player places a sign and starts writing text, but does not finish, another player can edit the text on the sign if he does not have permission to destroy the sign, but destroys it anyway,and places another sign in place of the original.(The second player must have finished writing the text before the original for the changes to take place.)
 * It is possible for Minecraft to crash if a server stopped while the player is editing a sign.
 * In snapshot 12w27a text on a sign could be entered, but moving out of render distance and coming back renders the sign blank. Also, all signs are blank upon bootup of the game. This is/was a rendering issue, and all text written on signs are still saved to the game file. This bug was found and dealt with by Dinnerbone almost immediately, however, it was not deemed vital enough to warrant a re-release of that week's snapshot.
 * Signs can be placed in Adventure Mode.
 * For players with old or integrated graphics cards, ever since the Beta 1.8 lighting update, signs as well as Chests will flash black at random intervals or just stay black. This can make signs very hard to read.
 * If a sign is visible while in the inventory (by opening the inventory when the sign is on the side of the screen) and the mouse is hovering over a block or item in the inventory, the sign will light up in the same manner as Item Frames(Tested in PC Creative).

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