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=The Players X Command=
From version 1.09 onward, the player setting can be changed arbitrarily in Single Player mode, open battle.net and non battle.net Mulitplayer mode. In order to do so, one has to enter a certain command while in game. This is done by hitting "Enter", typing the players X command, and confirming by hitting "Enter" again (yes, it's the normal shoutbox usage). The command differs slightly for the different versions of Diablo II.
This command is available in all versions of 1.10 and 1.11.