First point: head left or just any side of the head?

[geobao]

I am looking at oriented annotations for ships in DOTA v1.0. The paper of DOTA says:

To make a more detailed annotation, as illustrated Fig. 3, we emphasize the importance of the first point (x1,y1), which normally implies the “head” of the object. For helicopter, large vehicle, small vehicle, harbor, baseball diamond, ship and plane, we carefully denote their first point to enrich potential usages.

Does it mean that the first point can correspond to either the left or right of the head?

I have been exploring the annotations with my own visualization code and I observe that in most of the cases corresponds to the left of the head. But in a few cases it corresponds to the right of the head. Now I am unsure whether if my code is wrong or the annotations are on the head regardless of left or right.

So, what is the rule?