As a Project develops a number of Datums are automatically created. These Datums are linked to various items within the model and allow you to adjust key properties of the model items.
Datums are displayed in the Levels palette:
When there is no selection, key Datums in the Project are shown as a simple line. When an item is selected, then the Datums that are linked to the selected item are shown along with their name and height:
When a Building is created, Datums for the base (based on the current Working Level) and Roof are created, along with all the Levels in the Building.
All Buildings have their own independent Datums allowing you to easily manage different floor-to-floor heights across individual buildings without impacting other buildings in the project.