code: def hdrtxt(xmethod, dmethod, opt):
      
  
      txt = ['Itn', 'Fnc', 'DFid', u('ℓ1'), 'Cnstr']
      if xmethod == 'admm':
          txt.extend(['r_X', 's_X', u('ρ_X')])
      else:
          if opt['CBPDN', 'BackTrack', 'Enabled']:
              txt.extend(['F_X', 'Q_X', 'It_X', 'L_X'])
          else:
              txt.append('L_X')
      if dmethod != 'fista':
          txt.extend(['r_D', 's_D', u('ρ_D')])
      else:
          if opt['CCMOD', 'BackTrack', 'Enabled']:
              txt.extend(['F_D', 'Q_D', 'It_D', 'L_D'])
          else:
              txt.append('L_D')
      return txt
docs: Return ``hdrtxt`` argument for ``.IterStatsConfig`` initialiser.