About Datum Entity Creation in IDD
You can create datum entities such as datum curves, datum planes, datum points, datum axes, and datum coordinate systems in IDD. The same User Interface and workflow used to create datum features are also used to create most of the IDD datum entities.
Datum entities created in IDD are not stand alone features; they become a part of the imported feature. Hence, the resulting entities lose all their references upon creation and you cannot edit their definition. You can create all the datum entities asynchronously except for UV curves. Newly created datums are added as separate nodes on the GTS Tree, except UV curves, which are considered part of the surface they are defined on. Datum nodes are placed in the currently active node. If there is no currently active node, they are placed in the Datums Bin node, which is a collector node displayed as a base-level node. Datum nodes are never created as individual base-level nodes. You may reference any geometry of the import feature or any geometry of features that come before the import feature in the feature list of the model to create the datums.