[This is preliminary documentation and subject to change.]
Angle of arrow anti-clockwise to right horizontal in degrees.
The code relating to this property in the Draw method is a bit weird. Internally, all rotations are clockwise [this is by accient, I wasn't concentrating when I was doing it and was half done before I realised]. The simplest way to make angle represent anti-clockwise rotation (as it is normal to do) is to make the get and set methods negate the provided value.
ArrowItem Class | NPlot Namespace