ZingChart: Can I place marks such as a vertical line or bars with text in the graph?

In your scale object you can include any number of lines and or regions which can be used to indicate thresholds, ranges, plot bands, etc. In ZingChart these are defined in a markers:[{},{}]  array of objects.  Each marker object can also include a label.

All Documentation referenced here:

https://www.zingchart.com/docs/tutorials/chart-elements/markers/