A1 and A2 are the start and end angles in degrees, measured counter-clockwise from the positive $x$ axis. The arc is always swept counter-clockwise from A1 to A2, which is the DXF convention; to sweep the other way, exchange the two angles.

Equal start and end angles describe a full circle, since the two bound a sweep of 360 degrees. Prefer circle when that is what is meant.

Source Code: draw.Drawing