RIP database ER-Diagram II : foreign keys

                                                                             
 +-------------+               +-------------+               +-------------+ 
 | e_mail      |               | notify      |               | last        | 
 +-------------+               +-------------+        N    n +-------------+ 
 | object_id   |               | object_id   o--------}-+--}-o serial      | 
 | e_mail      |               |*notify      |          |    | prev_serial | 
 | object_type |               | object_type |          |    | object      | 
 +-------------+               +-------------+          |    +-------------+ 
                                                        |                    
                               +-------------+          |                    
                               | cross_nfy   |          |                    
                               +-------------+        N |                    
                               | object_id   o--------}-+                    
                               |*notify      |          |                    
                               | object_type |          |                    
                               +-------------+          |                    
                                                        |                    
                               +----------------+       |                    
                               | mnt_mnt_notify |       |                    
                               +----------------+     N |                    
                               | mnt_id         o-----}-+                    
                               |*mnt_nfy        |       |                    
                               +----------------+       |                    
                                                        |                    
                               +------------+           |                    
                               | mnt_upd_to |           |                    
                               +------------+         N |                    
                               | mnt_id     o---------}-+                    
                               |*upd_to     |                                
                               +------------+                                
                                                                             
                                                                             
                                                                             
 +-------------+               +-------------+               +-------------+ 
 | person_role |               | admin_c     |               | last        | 
 +-------------+        1      +-------------+        N    n +-------------+ 
 | pe_ro_id    o--------}-+  M | object_id   o--------}-+--}-o serial      | 
 | is_person   |          +--}-o pe_ro_id    |          |    | prev_serial | 
 |*nic_hdl     |          |    | object_type |          |    | object      | 
 +-------------+          |    +-------------+          |    +-------------+ 
                          |                             |                    
 +----------+             |    +-----------+            |                    
 | names    |             |    | li_author |            |                    
 +----------+           m |    +-----------+          N |                    
 | pe_ro_id o-----------}-+  M | li_id     o----------}-+                    
 |*name     |             +--}-o pe_ro_id  |            |                    
 +----------+             |    +-----------+            |                    
                          |                             |                    
                          |    +-------------+          |                    
                          |    | tech_c      |          |                    
                          |    +-------------+        N |                    
                          |  M | object_id   o--------}-+                    
                          |--}-o pe_ro_id    |          |                    
                          |    | object_type |          |                    
                          |    +-------------+          |                    
                          |                             |                    
                          |    +-------------+          |                    
                          |    | zone_c      |          |                    
                          |    +-------------+        N |                    
                          |  M | object_id   o--------}-+                    
                          +--}-o pe_ro_id    |                               
                               | object_type |                               
                               +-------------+                               
                                                                             
                                                                             
                                                                             
 +--------+                    +-------------+               +-------------+ 
 | mntner |                    | cross_mnt   |               | last        | 
 +--------+                    +-------------+        N    n +-------------+ 
 | mnt_id |                    | object_id   o--------}-+--}-o serial      | 
 | mntner |                    |*mntner      |          |    | prev_serial | 
 +--------+                    | object_type |          |    | object      | 
                               +-------------+          |    +-------------+ 
                                                        |                    
                               +-------------+          |                    
                               | mbrs_by_ref |          |                    
                               +-------------+        N |                    
                               | object_id   o--------}-+                    
                               |*mntner      |          |                    
                               | object_type |          |                    
                               +-------------+          |                    
                                                        |                    
                               +-------------+          |                    
                               | mnt_by      |          |                    
                               +-------------+        N |                    
                               | object_id   o--------}-+                    
                               |*mntner      |          |                    
                               | object_type |          |                    
                               +-------------+          |                    
                                                        |                    
                               +-------------+          |                    
                               | mnt_lower   |          |                    
                               +-------------+        N |                    
                               | object_id   o--------}-+                    
                               |*mntner      |                               
                               | object_type |                               
                               +-------------+                               
                                                                             
                                                                             
                                                                             
                                                                             
                               +----------+                  +-------------+ 
                               | mnt_auth |                  | last        | 
                               +----------+           N    n +-------------+ 
                               | mnt_id   o-----------}-+--}-o serial      | 
                               |*auth     |                  | prev_serial | 
                               +----------+                  | object      | 
                                                             +-------------+ 
                                                                             
                                                                             
                                                                             
                                                                             
 +--------+                    +------------+                +-------------+ 
 | domain |                    | dn_dom_net |                | last        | 
 +--------+                    +------------+         N    n +-------------+ 
 | dn_id  |                    | dn_id      o---------}-+--}-o serial      | 
 | domain |                    |*network    |           |    | prev_serial | 
 | type   |                    +------------+           |    | object      | 
 | port   |                                             |    +-------------+ 
 | host   |                    +------------+           |                    
 +--------+                    | dn_nserver |           |                    
                               +------------+         N |                    
                               | dn_id      o---------}-+                    
                               |*host       |           |                    
                               +------------+           |                    
                                                        |                    
                               +------------+           |                    
                               | dn_sub_dom |           |                    
                               +------------+         N |                    
                               | dn_id      o---------}-+                    
                               |*domain     |           |                    
                               +------------+           |                    
                                                        |                    
                               +------------+           |                    
                               | in_rev_srv |           |                    
                               +------------+         N |                    
                               | in_id      o---------}-+                    
                               |*rev_srv    |           |                    
                               +------------+           |                    
                                                        |                    
                               +------------+           |                    
                               | i6_rev_srv |           |                    
                               +------------+         N |                    
                               | i6_id      o---------}-+                    
                               |*rev_srv    |                                
                               +------------+                                
                                                                             
                                                                             
                                                                             
                                                                             
 +---------+                   +---------------+             +-------------+ 
 | aut_num |                   | route         |             | last        | 
 +---------+                   +---------------+      N    n +-------------+ 
 | an_id   |                   | rt_id         o------}-+--}-o serial      | 
 | aut_num |                   | prefix        |        |    | prev_serial | 
 +---------+                   | prefix_length |        |    | object      | 
                               |*origin        |        |    +-------------+ 
                               +---------------+        |                    
                                                        |                    
                               +----------+             |                    
                               | inet_rtr |             |                    
                               +----------+           N |                    
                               | ir_id    o-----------}-+                    
                               | inet_rtr |             |                    
                               |*local_as |             |                    
                               +----------+             |                    
                                                        |                    
                               +-------+                |                    
                               | peer  |                |                    
                               +-------+              N |                    
                               | ir_id o--------------}-+                    
                               | peer  |                                     
                               +-------+                                     
                                                                             
                                                                             
                                                                             
 +--------+                    +-------------+               +-------------+ 
 | as_set |                    | member_of   |               | last        | 
 +--------+             1    M +-------------+        N    n +-------------+ 
 | as_id  o-------------}-+--}-| object_id   o--------}-+--}-o serial      | 
 |*as_set |               |    | set_id      |               | prev_serial | 
 +--------+               |    | object_type |               | object      | 
                          |    +-------------+               +-------------+ 
 +------------+           |                                                  
 | filter_set |           |                                                  
 +------------+         1 |                                                  
 | fs_id      o---------}-+                                                  
 |*filter_set |           |                                                  
 | filter     |           |                                                  
 +------------+           |                                                  
                          |                                                  
 +-------------+          |                                                  
 | peering_set |          |                                                  
 +-------------+        1 |                                                  
 | ps_id       o--------}-+                                                  
 |*peering_set |          |                                                  
 +-------------+          |                                                  
                          |                                                  
 +-----------+            |                                                  
 | route_set |            |                                                  
 +-----------+          1 |                                                  
 | rs_id     o----------}-+                                                  
 |*route_set |            |                                                  
 +-----------+            |                                                  
                          |                                                  
 +-----------+            |                                                  
 | rtr_set   |            |                                                  
 +-----------+          1 |                                                  
 |           o----------}-+                                                  
 |*          |                                                               
 +-----------+