// Entity-Relationship model of a domain name registry.
// In Graphviz' "dot" format

graph registry {
  
  label = "Entity-Relationship model of the registry";
  overlap = scale;

   // Entities 
  node [shape=box, fontsize=20];
     Domains;
     Hosts;
     Contacts;
     Registrars;
     Authentication;
     Forbidden;
  
  // Attributes
  node [shape=ellipse, fontsize=10];
     Label;
     Status;
     Handle;
     Address;
     IPaddress;
     {node [label="Name"] NameHost; NameRegistrar;}

  // Attributes of entities
  edge [len=1.0];
    Status -- Domains;
    Label -- Domains;
    Contacts -- Handle;
    Contacts -- Address;
    Hosts -- IPaddress;
    Hosts -- NameHost;
    Registrars -- NameRegistrar;

  // Relationships 
  node [shape=diamond, fontsize=14];
     "D-C" [label="Tech, Admin\n or Holder"];
     "H-D" [label="Nameservers"];
     "H-P" [label="Parent"];
     "D-R";
     "R-C";
     "A-C";
     "C-C" [label=Maintains];
     "D-D" [label="Parent"];
  
  // Links 
  edge [len=1.3];
     Domains -- "D-D" [label="1"];
     Domains -- "D-D" [label="n"];
     Domains -- "D-C" [label="n"];
     Contacts -- "D-C" [label="n"];
     Registrars -- "R-C" [label="n"];
     Contacts -- "R-C" [label="n"];
     Domains -- "H-D" [label="n"];
     Hosts -- "H-D" [label="n"];
     Domains -- "H-P" [label="n"];
     Hosts -- "H-P" [label="1"];
     Domains -- "D-R" [label="1"];
     Registrars -- "D-R" [label="n"];
     Authentication -- "A-C" [label="n"];
     Contacts -- "A-C" [label="1"];
     Contacts -- "C-C" [label="n"];
     Contacts -- "C-C" [label="n"];
}