@OPEN 

@open <dir>[/<source>] [=<number>]. Creates an exit in the specified 
direction(s). If <number> is specified, it is linked to that room/object. 
If the optional <source> is specified, the exit is created attached to the
that object.  Otherwise, it is created unlinked. You or anyone else may use
the '@link' command to specify where the unlinked exit leads.  An exit can
have several aliases, using the semi-colon.  

Example: '@open w;west;out;exit;leave = #1234'