Thanks. But when I try to set up the perform task step and fill in variables from the list of variables, none of my task's defined local variables exist in the list. Not sure if this is by design.
Meanwhile, I have put the data I want to pass into the notification title/text. I then perform a task from the notification action that uses the Notification Listener addon to query notifications shown by Tasker and search them for the data I seek inside the title/text. This works. But seems an ugly hack.
And I have determined that a global variable usage would end up being an ugly thing as well because there might be more than one such notification in my scheme of things.