Specifies that coordinates are in the device coordinate context. On a computer screen the device coordinates are usually measured in pixels.
Specifies that coordinates are in the page coordinate context. Their units are defined by the System.Drawing.Graphics.PageUnit property, and must be one of the elements of the System.Drawing.GraphicsUnit enumeration.
Specifies that coordinates are in the world coordinate context. World coordinates are used in a nonphysical environment, such as a modeling environment.