There are three types of Milestones in Planera:
Start Milestone - One is required, and this is where you set the start date of the project
Interim Milestone - You can add as many as you like, and this is to track important Interim deadlines.
Constraints available on Interim Milestone:
Start On
Finish On
Start On or After
Finish On or Before
As Late As Possible
Finish Milestone - You can add one of these to the project.
Constraints available on Finish Milestone:
Finish On
Finish On or Before
How to add Milestones to the project
Using Left Toolbar
Hover over the left Toolbar and select the Milestones
Select the type of Milestone and click on the desired spot on the canvas to add it. A Milestone will be created in that spot.
Right click on the canvas and select “Interim Milestone”. A Milestone will be created in that spot.