Use the middle mouse button to place a Ping, indicating locations for your friends in multiplayer games.
When the cursor is aimed at a block, a Ping will be created at the corresponding location of the block. When the cursor is aimed at an entity, a Ping will be created above the entity's head.
By default, the middle mouse button creates a Ping that says Marks a location.. When pointing at an unfriendly entity, it creates There are enemy here..
Additionally, you can use the numeric keypad keys 1, 2, and 3 to create Pings that say Be careful here., Go here., and There are enemy here. respectively.

External resources
Project members
Gu-ZT
Member
Technical information
License
LGPL-3.0-or-later
Client side
required
Server side
required
Project ID
