I have seen many programmers getting confused between Features and tasks. Features are going to be part of Product Backlog and Tasks, are added by the developers into iteration backlog.
Features/Requirements are given by the Product owner. Iteration Backlog should contain only those tasks that would add value to the customer. There are certain tasks that need not be mentioned explicity. For ex: Refactoring, if you are following TDD.
It is assumed by default that Refactoring is going to be part of TDD(TFD + Refactoring). But, until the team gains profeciency in this area, they might have to explicity mention it in iteration backlog.
Similarly, Unit testing. If you are following TDD, then adding a task like "Coding..." would imply by default that, unit testing is done.