Multiplayer
To challenge another player to a contest of skill in battle, you can issue a duel. Killing a player who you are in a duel with incurs no penalties (though keep in mind, combat of any kind is outlawed in the vicinity of most stations.)
/duel challenge
/duel accept
/duel decline
/duel abort requests to call a truce. No victor is recorded.
/duel forfeit forfeits the duel. The other player is recorded as the winner.