Breaking a task into subtasks
Split a Rhazes task that is really several jobs into subtasks so partial progress is visible, and what happens when you delete the parent.
Updated
When to split one
A task like "sort out Mr Okafor's discharge" is not one job. Splitting it into subtasks lets you see what is actually left rather than looking at a single item that never gets ticked.
How they behave
Subtasks sit under their parent and are completed individually, so partial progress is visible instead of invisible.
Deleting the parent
Deleting a task deletes its subtasks with it. That is usually what you want, since subtasks of an abandoned job are rarely worth keeping, but it is worth knowing before you delete a parent with real work under it.
Do not over-split
Two or three subtasks make a task clearer. Ten make a second to-do list inside your to-do list, which is harder to read than the thing it replaced.