Dynamic Chart Reference Lines

Reference lines help us add context to the charts, we can set ones that are fixed, e.g. when we know the target for a KPI, or calculated ones like the average, minimum, or maximum value of a metric.

But what if we don't know the KPI target beforehand and want to allow the viewer to decide where to put the reference line?

We can achieve this by using a Parameter as the value for the reference line.