In CGM, datas can be stored in an abstract Virtual Device Coordinates (VDC) or in a metric VDC. By default GPHIGS creates an abstract VDC for all CGM driver type. Setting the %ds directive with workstation type 12 and 13 will change the default behaviour to metric. %ds defines the metric space.
In metric space default marker size and line width are defined in metre. Default line width is 0.35 millimetres and default marker size is 2.5 millimetres.
Hatching is realized assuming that 1 hatch unit = 0.1 millimetre. Thus if Interior Style index is set to 45015, hatch angle will be 45 degrees and spacing between hatches will be 1.5 millimeters.