Open Source Charting Library With Vertical Markers/Annotations

15 Nov 2014 Saw this charting library from the Mozilla Metrics Team on hacker news recently: http://metricsgraphicsjs.org/interactive-demo.htm

Their interactive example is here: http://metricsgraphicsjs.org/interactive-demo.htm

I'm not aware of any other charting libraries besides highcharts that do vertical marker lines this easily.