def stringify_qns(field):
    """Returns a string representation of a field."""
    if field.label not in {"L", "Q", "ub", "db", "eb", "H"}:
        lor = "S" if field.is_scalar else "F"
        _, _, cup, cdown, i = field.dynkin
        return f"{lor},{cup}{cdown},{i},{field.charges['y']},{field.charges['3b']}"

    return field.label + (".conj" if field.is_conj else "")