Which frame_id field in nav_msgs::Path should be used?

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The nav_msgs::Path contains a header field as well as an array of geometry_msgs/PoseStamped poses which have their own header fields.

So, while publishing a path, which header, global header or individual headers of poses, should be used to set the frame?

If it's a developer's choice, is any of these two options preferred to make a package interoperable with other existing packages in ROS ecosystem?

Would really appreciate if you could provide your thoughts on this message type's frame information.

Thank you!