Format

    global-field-name

    [            {BIT       }                            ]
    [            {BYTE      }                            ]
    [ ALIGNED ON {WORD      } BOUNDARY                   ]
    [            {LONGWORD  }                            ]
    [            {QUADWORD  }                            ]
    [            {OCTAWORD  }                            ] .
    [ NOALIGNED                                          ]
    [                                 [                ] ]
    [ CONSTRAINT constr-name NOT NULL [DEFERRABLE      ] ]
    [                                 [NOT DEFERRABLE  ] ]
    [                                                    ]