Revision
When a error occurs during task control, project manager markes it as incorrect task and the task returns to related user. But when there is no mistake in the task, tasks can be sent to user for revision after the task is delivered. There is no difference between revision tasks and normal tasks.
To reach revision panel, you need to be manager of related task. After the task is completed, you can open the revision task by opening related panel with sending back icon in the client control field and filling classic task fields.
There is no difference between the calculations of revision tasks and normal tasks.