Please note: This a new feature that was introduced during maintenance on September 10th, 2017.
If you are creating a new plan, you have the option to save it as a Draft, so you can come back to complete it, before publishing it.
The option to Draft is at the bottom of the page, beside the option to Publish.
Once you have selected Draft, the plan will save, and you will be redirected to the Draft Plans section of Planning. You can access the draft plan by clicking on the plan's title.
You will also be able to access the Draft Plans section from the Active Plans page by clicking on the Draft Plans button.