About Ordinate Baselines
Ordinate baseline annotation elements are reference baselines that you can use to create ordinate dimensions. All dimensions that reference the same baseline must share a common plane. You can use an existing ordinate baseline Annotation Element or create a new one to create ordinate dimension Annotation Elements.
Baseline Annotation Elements are created inside an Annotation feature and reference model geometry or datums. You cannot make ordinate baseline Annotation Elements nongraphical as they do not have an equivalent 3D model annotation.