 The study of such relationships is ontology.Composite objects may be represented in storage by co-locating the composed items, by co-locating references, or in many other ways.The items within a composite object may be referred to as "attributes", "fields", "members", "properties", or other names, and the resulting composition as "composite type", "storage record", "structure", "tuple", or a "user-defined type (UDT)".