1. A method for multityping data using a schematized data model having a single inheritance hierarchy, the method comprising: defining a first abstract data construct in a schematized data model to contain data that most types of an object have in common; defining a second abstract data construct to contain data that is specific to a particular type of the object; defining a type of the first abstract data construct to describe the object's common data; defining a first type of the second abstract data construct to describe data that is specific to one particular type of the object; and attaching an instance of the first type of the second abstract data construct to an instance of the first abstract data construct type without altering a behavior of the first abstract data construct.