Format

      { EXACT_POSITIONING           }
      { ANY_CYLINDER                }
      { BEST_TRY_CONTIGUOUS         }
      {                             }
      { CONTIGUOUS                  }
      { POSITION position-type      }
      { VOLUME numeric-literal      }
      {                             }
      { ALLOCATE numeric-literal    }
      { BUCKET_SIZE numeric-literal }
      { EXTENSION numeric-literal   }
      {                             }