How does the robot get the goal point with map?

[AssassinCrow]

Hello, recently I read your paper and repository wrt this not bad package. :)

You mentioned the mobile robot should do navigate to the goal point without known-map,
and you wrote about it in here,

**def _callback_goal(self, data):
    """
    Callback of the goal subscriber from rviz,
    :param data: PoseWithCovarianceStamped.
    :return:
    """
    self._pose_goal = data**

What does it mean? How can I get the goal point from rviz, without known-map?

I have a feeling that it would be a great help to my works if I know how to do that. :)
Would you please teach me?

Thanks in advance. :)