Targets are what you aim commands at.

A target is always one of the below:
    <object name>     -- if it's nearby.
    #<object number> -- to avoid ambiguity, some cmds don't require #'s.
    *<player name>  -- for when they're not nearby.
    +<Group name>  -- for when it's not nearby.
    HERE          -- translates to the rooms number.
    ME           -- translates to user's number.
    HOME        -- translates to the user's home's room number.
    BACK       -- translates to the room number the BUILDER previous visited.
    THERE     -- translates to the room number the builder just dug.
    RETURN   -- sends the USER back wherever they came in from.

see also: here, me, home, back, there, return