def_table_constraint

def_table_constraint 
      ::= 
      ( ( ( "unique" | ( "primary" "key" ) ) "(" column_list ")" ) 
      | ( "foreign" "key" "(" column_list ")" 
      "references" [ schema_name "." ] table_name 
      [ "(" column_list ")" ] 
      [ "on" "delete" "cascade" ] ) 
      | ( "chek" "(" condition ")" ) 
      | ( [ "using" "index" index_storage { index_storage } ] 
      [ "exceptions" "into" [ schema_name "." ] table_name ] ) 
      | ( "disable" ) 
      ) 

This rule is called by

table_constraint