Object Type Constraints
Object Type Constraints (Inclusions) may be made by either Intersection or Union of up to three types, selected from 40 possible types. One object type can be selected from each of three different categories (Classified Extragalactic, Unclassified Extragalactic, and Components of Galaxies.) Any given object may have many different object types assigned from different journal articles, which are not necessarily consistent. For example, the Intersection of Galaxies (G) and H II Regions (H II) is not the empty set. Object Types Constraints (Exclusions) will exclude any object with any one of three selected object types selected from the three different categories.