The border defines the shape.
It is the contour, the perimeter, the surface that defines what the shape or the object is. That is true for this shape as it is drawn. It is probably also true for an organisation. What is inside gets meaning by its interaction with the outside.
We tend to focus on the inside of an organisation, its structure, the internal interactions and rules of engagement. But what is the point of that inside if it has no external meaning? So where inside and outside meet, it becomes exiting.
And what is inside? And what is outside?