the first table is aliased as 'o' and the linked table is aliased as 'l' (thats a lower case L if you cant tell)
The links always have to be between an o.{field} and a l.{field} like this:
link (l.host = o.obj_id) // the linked objects host will be the object we find
link (l.owner =o.obj_id) // the linked objects owner is the object we find.
link (l.loc = o.obj_id) // to find all objects contains the ones we are looking for
If your feeling adventerous