def createOrphanField(fieldset, address, field_cls, *args, **kw):
    """
    Create an orphan field at specified address:
      field_cls(fieldset, *args, **kw)

    The field uses the fieldset properties but it isn't added to the
    field set.
    """
    save_size = fieldset._current_size
    try:
        fieldset._current_size = address
        field = field_cls(fieldset, *args, **kw)
    finally:
        fieldset._current_size = save_size
    return field