Local defines sites that are considered local (same campus/organization).
These are used for the LCL FAC, for "Service= Local", and so on. They are
also used to  bypass DISTRIBUTE for these particular  hosts. You wouldn't
want your internal,  non-public list mail routed to  the closest INTERBIT
for delivery  just because you haven't  defined a site gateway  in DOMAIN
NAMES or whatever.
 
  Eric