We have a target line that we need to display on our chart (y axis is percentage, x axis is months). Currently we create a series mapping for this target line though the problem is if we are viewing for a single month we just see a single point on the chart, we need to see a horizontal rule. The custom grid line solves this problem though our target line can vary each month. Is it possible to bind the custom grid line to an items source or create a custom grid line with multiple different x and y points?