HCL Link UI settings
Some node types allow you to set flow variables using the HCL Link UI settings dialog, in the Flow Designer canvas.
Specifying a flow variable is a must for certain node types, in order for them to function properly during flow execution.
For example: A router node in a flow definition requires that a flow variable be defined for routing the data to one or more outputs of the node, based on the criteria applied over the flow variable and its value.