Indicates how nodes listen to events from other nodes in the Slony-I network.
Structure of sl_listen
li_origin integer
PRIMARY KEY
REFERENCES sl_node>
The ID # (from sl_node.no_id) of the node this listener is operating on
li_provider integer
PRIMARY KEY
REFERENCES sl_path>
The ID # (from sl_node.no_id) of the source node for this listening event
li_receiver integer
PRIMARY KEY
REFERENCES sl_path>
The ID # (from sl_node.no_id) of the target node for this listening event