Default Chart Refresh

According to this guide

a chart may be displayed in the browser by calling a specific URL.

The example given in the link above is



  1. The parameter random is not explained. What does is do?
  2. I’ve tried adding a parameter refresh to the URL but this doesn’t seem to do anything:

Is there a way to provide a URL that refreshes the chart automatically?

For my tests I’m currently using openHAB 1.8.3.