def isfld(xmethod, dmethod, opt):
    """Return ``isfld`` argument for ``.IterStatsConfig`` initialiser.
    """
    fld = ['Iter', 'ObjFun', 'DFid', 'RegL1', 'Cnstr']
    if xmethod == 'admm':
        fld.extend(['XPrRsdl', 'XDlRsdl', 'XRho'])
    elif opt['CBPDN', 'BackTrack', 'Enabled']:
        fld.extend(['X_F_Btrack', 'X_Q_Btrack', 'X_ItBt', 'X_L', 'X_Rsdl'])
    else:
        fld.extend(['X_L', 'X_Rsdl'])
    if dmethod != 'fista':
        fld.extend(['DPrRsdl', 'DDlRsdl', 'DRho'])
    elif opt['CCMOD', 'BackTrack', 'Enabled']:
        fld.extend(['D_F_Btrack', 'D_Q_Btrack', 'D_ItBt', 'D_L', 'D_Rsdl'])
    else:
        fld.extend(['D_L', 'D_Rsdl'])
    fld.append('Time')
    return fld
