Some collections are defined as the union of other collections. For example, MODERN EUROPEAN SCRIPTS (collection 283) is the union of more than 30 collections, each of which is a simple range. COMMON JAPANESE (collection 287) is defined as the union of BASIC JAPANESE (collection 285) and an enumerated list of 609 code points. Although it is possible to copy the definition of referenced collections and avoid references, the result would be less readable and harder to maintain.