Environment angle?

What is the environment angle for? How can I use that in my apps?

The environment has a perimeter that defines the coordinate space of an environment. The coordinate space is an x/y grid, but it may be more convenient to align the grid to the walls of the building than to compass north. For example, in New York City, the Manhattan street grid is actually oriented 29° from north. The environment object has an "angle" property that can store the number of degrees between north and the Y-axis of the coordinate space. This allows apps that use the compass to indicate the direction of a thing to compensate for the angle of the coordinate space and indicate the correct direction.