0',
                      stroke: 'white',
                      strokeWidth: 4
                    }),
                    // three differently sized tick marks
                    new go.Shape({ geometryString: 'M0 0 V10', stroke: 'white', strokeWidth: 1 }),
                    new go.Shape({
                      geometryString: 'M0 0 V12',
                      stroke: 'white',
                      strokeWidth: 2,
                      interval: 2
                    }),
                    new go.Shap