Combat Tag

Combat Tag is a plugin (source) which is used to balance combat. Formally, its plugin name is CombatTagPlus.

Combat Tagged
Whenever you take damage from another player, you are marked as "combat tagged" for a period of time (varies by server, but roughly 30 seconds). If you log out while tagged, your player's body will remain on the server for a period of time (varies by server, but roughly 30 seconds). Your body can still take damage and be killed while you are logged out. In particular you can still be pearled if you log out while combat tagged.

In addition, whenever you join the server, you are combat tagged for a short period of time (varies by server, but roughly 10 seconds).

Safe Logout
You can log out safely (without leaving behind a body) with the  command. This command requires a short duration without movement or taking damage to take effect (varies by server, but roughly 10 seconds).

Commands

 * or  - Check combat tag timer
 * - Logs out without leaving behind a body (requires a short duration without movement or taking damage to take effect)