The red vertical reference line points to the quarter when the demand is greater than the inventory.
The line varies from item to item.
I want to check the difference between demand and the inventory value for each quarter. When inventory-demand<0 for Q1, I want the vertical ref line to point to Q1. Otherwise, I want to check the condition for the next quarter Q2. This has to go on until Q4.
I read a link which says that I can do so using a calculated field. But I was not able to come up with a code.