code/modules/client/player_details.dm

/datum/player_details	Tracks information about a client between log in and log outs
/proc/log_played_names	Adds the new names to the player's played_names list on their /datum/player_details for use of admins. `ckey` should be their ckey, and `data` should be an associative list with the keys being the names they played under and the values being the unique mob ID tied to that name.