code: def initialise_arrays(group, f):
      
      for node in ['pos_x', 'pos_y', 'pos_z', 'dir_x', 'dir_y', 'dir_z', 'du',
                   'floor', 't0']:
          if node in ['floor', 'du']:
              atom = U1_ATOM
          else:
              atom = F4_ATOM
          f.create_earray(group, node, atom, (0, ), filters=FILTERS)
docs: Create EArrays for calibrated hits