def spline_backwards_hankel(ht, htarg, opt):
    r
    ht = ht.lower()
    if ht in ['fht', 'qwe', 'hqwe']:
        if ht == 'fht':
            htarg = _check_targ(htarg, ['fhtfilt', 'pts_per_dec'])
        elif ht in ['qwe', 'hqwe']:
            htarg = _check_targ(htarg, ['rtol', 'atol', 'nquad', 'maxint',
                                'pts_per_dec', 'diff_quad', 'a', 'b', 'limit'])
        if opt == 'spline':
            mesg = ("\n    The use of `opt='spline'` is deprecated and will " +
                    "be removed\n    in v2.0.0; use the corresponding " +
                    "setting in `htarg`.")
            warnings.warn(mesg, DeprecationWarning)
            opt = None
            if 'pts_per_dec' not in htarg:
                if ht == 'fht':
                    htarg['pts_per_dec'] = -1
                elif ht in ['qwe', 'hqwe']:
                    htarg['pts_per_dec'] = 80
    return htarg, opt