The Scrum Issue Type Scheme comes with Epic, Story, Bug, and Improvement as first level "issues". Technical tasks can be created as children of stories, but not as first level cards.
I was thinking of using "improvement" cards to represent work like refactoring, or non-user exposed technical tasks that don't relate to a specific user story. (This would elimiinate my need to go through the IT department to reconfigure my project to include a new "Task" card type).
Before I do that, though, I'd like to understand what the "improvement" concept was initially intended for in an agile context. It appears to me that it is simply a carryover from the default scheme from my research so far.
Thanks,
Adrian