this

_this, this and thislist

_this contains the given arguments in a script/function, executed by exec, execVM or call. For the arguments in scripts executed by mission-made actions check Comments of addAction.

this is used for config-made actions (contains the object which was the action attached to), in initlines (containing the object which the initline belongs to) and last but not least in condition lines of trigger this stands for the conditions you set in the trigger (like "East Not Present" etc).

thislist can only be used in the OnActivation line of a trigger and contains the same as the list command (thislist is obviously referring to the trigger's list).