To address various orbital evolutions of spacecrafts, some particular orbital charts are taken into account. For example, the following is used to depict how a chaser reaches a target:
The only thing that I know about this notation is its frame definition, based on which +X is the horizontal axis toward left, and +Z is downward. But I have no idea about the rest, say, the curves, their size variations, those black squares, etc.
Does anyone know any reference in which the interpretation of this graphical notation is thoroughly discussed?